Google Translate TTS API blocked - google-text-to-speech

Google implemented a captcha to block people from accessing the TTS translate API https://translate.google.com/translate_tts?ie=UTF-8&q=test&tl=zh-TW. I was using it in my mobile application. Now, it is not returning anything. How do I get around the captcha?

Add the qualifier '&client=tw-ob' to the end of your query.
https://translate.google.com/translate_tts?ie=UTF-8&q=test&tl=zh-TW&client=tw-ob
This answer no longer works consistently. Your ip address will be blocked by google temporarily if you abuse this too much.

there are 3 main issues:
you must include "client" in your query string (client=t seems to work).
(in case you are trying to retrieve it using AJAX) the Referer of the HTTP request must be https://translate.google.com/
"tk" field changes for every query, and it must be populated with a matching hash:
tk = hash(q, TKK), where q is the text to be TTSed, and TKK is a var in the global scope when you load translate.google.com: (type 'window.TKK' in the console). see the hash function at the bottom of this reply (calcHash).
to summarize:
function generateGoogleTTSLink(q, tl, tkk) {
var tk = calcHash(q, tkk);
return `https://translate.google.com/translate_tts?ie=UTF-8&total=1&idx=0&client=t&ttsspeed=1&tl=${tl}&tk=${tk}&q=${q}&textlen=${q.length}`;
}
generateGoogleTTSLink('ciao', 'it', '410353.1336369826');
// see definition of "calcHash" in the bottom of this comment.
=> to get your hands on a TKK, you can open Google Translate website, then type "TKK" in developer tools' console (e.g.: "410353.1336369826").
NOTE that TKK value changes every hour, and so, old TKKs might get blocked at some point, and refreshing it may be necessary (although so far it seems like old keys can work for a LONG time).
if you DO wish to periodically refresh TKK, it can be automated pretty easily, but not if you're running your code from the browser.
you can find a full NodeJS implementation here:
https://github.com/guyrotem/google-translate-server.
it exposes a minimal TTS API (query, language), and is deployed to a free Heroku server, so you can test it online if you like.
function shiftLeftOrRightThenSumOrXor(num, opArray) {
return opArray.reduce((acc, opString) => {
var op1 = opString[1]; // '+' | '-' ~ SUM | XOR
var op2 = opString[0]; // '+' | '^' ~ SLL | SRL
var xd = opString[2]; // [0-9a-f]
var shiftAmount = hexCharAsNumber(xd);
var mask = (op1 == '+') ? acc >>> shiftAmount : acc << shiftAmount;
return (op2 == '+') ? (acc + mask & 0xffffffff) : (acc ^ mask);
}, num);
}
function hexCharAsNumber(xd) {
return (xd >= 'a') ? xd.charCodeAt(0) - 87 : Number(xd);
}
function transformQuery(query) {
for (var e = [], f = 0, g = 0; g < query.length; g++) {
var l = query.charCodeAt(g);
if (l < 128) {
e[f++] = l; // 0{l[6-0]}
} else if (l < 2048) {
e[f++] = l >> 6 | 0xC0; // 110{l[10-6]}
e[f++] = l & 0x3F | 0x80; // 10{l[5-0]}
} else if (0xD800 == (l & 0xFC00) && g + 1 < query.length && 0xDC00 == (query.charCodeAt(g + 1) & 0xFC00)) {
// that's pretty rare... (avoid ovf?)
l = (1 << 16) + ((l & 0x03FF) << 10) + (query.charCodeAt(++g) & 0x03FF);
e[f++] = l >> 18 | 0xF0; // 111100{l[9-8*]}
e[f++] = l >> 12 & 0x3F | 0x80; // 10{l[7*-2]}
e[f++] = l & 0x3F | 0x80; // 10{(l+1)[5-0]}
} else {
e[f++] = l >> 12 | 0xE0; // 1110{l[15-12]}
e[f++] = l >> 6 & 0x3F | 0x80; // 10{l[11-6]}
e[f++] = l & 0x3F | 0x80; // 10{l[5-0]}
}
}
return e;
}
function normalizeHash(encondindRound2) {
if (encondindRound2 < 0) {
encondindRound2 = (encondindRound2 & 0x7fffffff) + 0x80000000;
}
return encondindRound2 % 1E6;
}
function calcHash(query, windowTkk) {
// STEP 1: spread the the query char codes on a byte-array, 1-3 bytes per char
var bytesArray = transformQuery(query);
// STEP 2: starting with TKK index, add the array from last step one-by-one, and do 2 rounds of shift+add/xor
var d = windowTkk.split('.');
var tkkIndex = Number(d[0]) || 0;
var tkkKey = Number(d[1]) || 0;
var encondingRound1 = bytesArray.reduce((acc, current) => {
acc += current;
return shiftLeftOrRightThenSumOrXor(acc, ['+-a', '^+6'])
}, tkkIndex);
// STEP 3: apply 3 rounds of shift+add/xor and XOR with they TKK key
var encondingRound2 = shiftLeftOrRightThenSumOrXor(encondingRound1, ['+-3', '^+b', '+-f']) ^ tkkKey;
// STEP 4: Normalize to 2s complement & format
var normalizedResult = normalizeHash(encondingRound2);
return normalizedResult.toString() + "." + (normalizedResult ^ tkkIndex)
}
// usage example:
var tk = calcHash('hola', '409837.2120040981');
console.log('tk=' + tk);
// OUTPUT: 'tk=70528.480109'

You can also try this format :
pass q= urlencode format of your language
(In JavaScript you can use the encodeURI() function & PHP has the rawurlencode() function)
pass tl = language short name (suppose bangla = bn)
Now try this :
https://translate.google.com.vn/translate_tts?ie=UTF-8&q=%E0%A6%A2%E0%A6%BE%E0%A6%95%E0%A6%BE+&tl=bn&client=tw-ob

First, to avoid captcha, you have to set a proper user-agent like: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:46.0) Gecko/20100101 Firefox/46.0"
Then to not being blocked you must provide a proper token ("tk" get parameter) for each single request.
On the web you can find many different kind of scripts that try to calculate the token after a lot of reverse engineering...but every time the big G change the algorithm you're stuck again, so it's much easier to retrieve your token just observing in deep similar requests to translate page (with your text in the url).
You can read the token time by time grepping "tk=" from the output of this simple code with phantomjs:
"use strict";
var page = require('webpage').create();
var system = require('system');
var args = system.args;
if (args.length != 2) { console.log("usage: "+args[0]+" text"); phantom.exit(1); }
page.onConsoleMessage = function(msg) { console.log(msg); };
page.onResourceRequested = function(request) { console.log('Request ' + JSON.stringify(request, undefined, 4)); };
page.open("https://translate.google.it/?hl=it&tab=wT#fr/it/"+args[1], function(status) {
if (status === "success") { phantom.exit(0); }
else { phantom.exit(1); }
});
so in the end you can get your speech with something like:
wget -U "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:46.0) Gecko/20100101 Firefox/46.0"
"http://translate.google.com/translate_tts?ie=UTF-8&tl=it&tk=52269.458629&q=ciao&client=t" -O ciao.mp3
(token are probably time based so this link may not work tomorrow)

I rewrote Guy Rotem's answer in Java, so if you prefer Java over Javascript, feel free to use:
public class Hasher {
public long shiftLeftOrRightThenSumOrXor(long num, String[] opArray) {
long result = num;
int current = 0;
while (current < opArray.length) {
char op1 = opArray[current].charAt(1); // '+' | '-' ~ SUM | XOR
char op2 = opArray[current].charAt(0); // '+' | '^' ~ SLL | SRL
char xd = opArray[current].charAt(2); // [0-9a-f]
assertError(op1 == '+'
|| op1 == '-', "Invalid OP: " + op1);
assertError(op2 == '+'
|| op2 == '^', "Invalid OP: " + op2);
assertError(('0' <= xd && xd <= '9')
|| ('a' <= xd && xd <='f'), "Not an 0x? value: " + xd);
int shiftAmount = hexCharAsNumber(xd);
int mask = (op1 == '+') ? ((int) result) >>> shiftAmount : ((int) result) << shiftAmount;
long subresult = (op2 == '+') ? (((int) result) + ((int) mask) & 0xffffffff)
: (((int) result) ^ mask);
result = subresult;
current++;
}
return result;
}
public void assertError(boolean cond, String e) {
if (!cond) {
System.err.println();
}
}
public int hexCharAsNumber(char xd) {
return (xd >= 'a') ? xd - 87 : Character.getNumericValue(xd);
}
public int[] transformQuery(String query) {
int[] e = new int[1000];
int resultSize = 1000;
for (int f = 0, g = 0; g < query.length(); g++) {
int l = query.charAt(g);
if (l < 128) {
e[f++] = l; // 0{l[6-0]}
} else if (l < 2048) {
e[f++] = l >> 6 | 0xC0; // 110{l[10-6]}
e[f++] = l & 0x3F | 0x80; // 10{l[5-0]}
} else if (0xD800 == (l & 0xFC00) &&
g + 1 < query.length() && 0xDC00 == (query.charAt(g + 1) & 0xFC00)) {
// that's pretty rare... (avoid ovf?)
l = (1 << 16) + ((l & 0x03FF) << 10) + (query.charAt(++g) & 0x03FF);
e[f++] = l >> 18 | 0xF0; // 111100{l[9-8*]}
e[f++] = l >> 12 & 0x3F | 0x80; // 10{l[7*-2]}
e[f++] = l & 0x3F | 0x80; // 10{(l+1)[5-0]}
} else {
e[f++] = l >> 12 | 0xE0; // 1110{l[15-12]}
e[f++] = l >> 6 & 0x3F | 0x80; // 10{l[11-6]}
e[f++] = l & 0x3F | 0x80; // 10{l[5-0]}
}
resultSize = f;
}
return Arrays.copyOf(e, resultSize);
}
public long normalizeHash(long encondindRound2) {
if (encondindRound2 < 0) {
encondindRound2 = (encondindRound2 & 0x7fffffff) + 0x80000000L;
}
return (encondindRound2) % 1_000_000;
}
/*
/ EXAMPLE:
/
/ INPUT: query: 'hola', windowTkk: '409837.2120040981'
/ OUTPUT: '70528.480109'
/
*/
public String calcHash(String query, String windowTkk) {
// STEP 1: spread the the query char codes on a byte-array, 1-3 bytes per char
int[] bytesArray = transformQuery(query);
// STEP 2: starting with TKK index,
// add the array from last step one-by-one, and do 2 rounds of shift+add/xor
String[] d = windowTkk.split("\\.");
int tkkIndex = 0;
try {
tkkIndex = Integer.valueOf(d[0]);
}
catch (Exception e) {
e.printStackTrace();
}
long tkkKey = 0;
try {
tkkKey = Long.valueOf(d[1]);
}
catch (Exception e) {
e.printStackTrace();
}
int current = 0;
long result = tkkIndex;
while (current < bytesArray.length) {
result += bytesArray[current];
long subresult = shiftLeftOrRightThenSumOrXor(result,
new String[] {"+-a", "^+6"});
result = subresult;
current++;
}
long encondingRound1 = result;
//System.out.println("encodingRound1: " + encondingRound1);
// STEP 3: apply 3 rounds of shift+add/xor and XOR with they TKK key
long encondingRound2 = ((int) shiftLeftOrRightThenSumOrXor(encondingRound1,
new String[] {"+-3", "^+b", "+-f"})) ^ ((int) tkkKey);
//System.out.println("encodingRound2: " + encondingRound2);
// STEP 4: Normalize to 2s complement & format
long normalizedResult = normalizeHash(encondingRound2);
//System.out.println("normalizedResult: " + normalizedResult);
return String.valueOf(normalizedResult) + "."
+ (((int) normalizedResult) ^ (tkkIndex));
}
}

Related

How to format a number into thousands, millions and billions with dart/flutter?

How to get a number converted into something like this: 12K, 1.5M, 4.2B from a normal number like: 134900.
This is a minimalist function, of course you'll have to add validation code to verify if the number is valid before executing the function. Otherwise Enjoy ...
void main() {
double num = 1250;
var myNumber = k_m_b_generator(num);
print(myNumber);
}
String k_m_b_generator(num) {
if (num > 999 && num < 99999) {
return "${(num / 1000).toStringAsFixed(1)} K";
} else if (num > 99999 && num < 999999) {
return "${(num / 1000).toStringAsFixed(0)} K";
} else if (num > 999999 && num < 999999999) {
return "${(num / 1000000).toStringAsFixed(1)} M";
} else if (num > 999999999) {
return "${(num / 1000000000).toStringAsFixed(1)} B";
} else {
return num.toString();
}
}
You can use flutter's NumberFormat class with the compact function.
formatNumber(dynamic myNumber) {
// Convert number into a string if it was not a string previously
String stringNumber = myNumber.toString();
// Convert number into double to be formatted.
// Default to zero if unable to do so
double doubleNumber = double.tryParse(stringNumber) ?? 0;
// Set number format to use
NumberFormat numberFormat = new NumberFormat.compact();
return numberFormat.format(doubleNumber);
}
The answer is not entirely correct. If you test it, you will see what i meant. Base on the answer above, I created this solution:
String numberFormat(int n) {
String num = n.toString();
int len = num.length;
if (n >= 1000 && n < 1000000) {
return num.substring(0, len - 3) + '.' + num.substring(len - 3, 1 + (len - 3)) + 'k';
} else if (n >= 1000000 && n < 1000000000) {
return num.substring(0, len - 6) + '.' + num.substring(len - 6, 1 + (len - 6)) + 'm';
} else if (n > 1000000000) {
return num.substring(0, len - 9) + '.' + num.substring(len - 9, 1 + (len - 9)) + 'b';
} else {
return num.toString();
}
}

Unable to print formatted text using Bluetooth printer

I can able to print the text, Arabic characters but i am unable to print the formatted text like align center, bold text etc
I am using this plugin to print data https://github.com/don/BluetoothSerial
below are the commands for align center and bold text.
TXT_ALIGN_CT: '\x1b\x61\x01', // Centering
TXT_BOLD_ON: '\x1b\x45\x01';
followed below steps :
1.using below function to convert string to byte
private getPrintData(TEXT: string) {
// based on http://ciaranj.blogspot.fr/2007/11/utf8-characters-encoding-in-javascript.html
var bytes = [];
for (var n = 0; n < TEXT.length; n++) {
var c = TEXT.charCodeAt(n);
if (c < 128) {
bytes[bytes.length] = c;
} else if ((c > 127) && (c < 2048)) {
bytes[bytes.length] = (c >> 6) | 192;
bytes[bytes.length] = (c & 63) | 128;
} else {
bytes[bytes.length] = (c >> 12) | 224;
bytes[bytes.length] = ((c >> 6) & 63) | 128;
bytes[bytes.length] = (c & 63) | 128;
}
}
return bytes;
}
const printData = this.getPrintData(getPrintData('你好'));
this.printer.printData(printData ).then((success) => {});
its working fine.
2. try to pass ESC/POS commands as hex code like below.
const data = new Uint8Array([0x2fa00bf0e86c440658a6a71]);
this.printer.printData(data);
its not displaying bold text,
can any one please help me ??
some of the printers doesn't supports the ESC/POS commands we have to use native sdks to resolve, i resolved by creating custom cordova plugin

Unicode escape in C

I m using CURL to retreive a JSON string from Wikipedia, eg
https://en.wikipedia.org/w/api.php?action=opensearch&limit=1&format=json&search=syntax
I don't use a JSON parser, and I am searching a way to remove the unicode part, which is useless for me.
I have already tried &utf8= in url, and WideCharToMultiByte and wcstombs.
I just want to convert this string to ANSI format, to be used in another application, even if I will lose data.
Here is the code I am using to convert the string:
void UnicodeToAnsi(char *str, char *str2)
{
unsigned char ch;
char *pr = str;
char *pw = str2;
while ( (*pr) != 0 )
{
ch = (*pr);
if ( ch == '\\' )
{
if ( *(pr+1) == 'u')
{
char szANSIString [2] = {'\0'};
wchar_t wcsString[2] = {0,'\0'};
char h[5]={'\0'};
int v;
strncpy(h,pr + 2,4);
v = (int)strtol(h, NULL, 16);
#if 0
wcsString[0] = v;
#ifndef _WIN32
WideCharToMultiByte ( CP_ACP, // ANSI code page
WC_COMPOSITECHECK, // Check for accented characters
wcsString, // Source Unicode string
-1, // -1 means string is zero-terminated
szANSIString, // Destination char string
sizeof(szANSIString), // Size of buffer
NULL, // No default character
NULL ); // Don't care about this flag
#else
wcstombs(szANSIString, wcsString, sizeof(szANSIString));
#endif
ch = *szANSIString;
if (ch == '\0') ch = '?';
#endif
//bored with this unicode, easy way
ch = '-';
if (v == 232) ch = 138;
if (v == 233) ch = 130;
if (v == 234) ch = 136;
if (v == 224) ch = 133;
if (v == 225) ch = 'a';
if (v == 226) ch = 'a';
if (v == 257) ch = 'a';
if (v == 231) ch = 135;
pr = pr + 5;
}
}
(*pw) = ch;
++pw;
++pr;
}
*pw = '\0';
return;
}

Small differences in SHA1 hashes

A project I am working on uses Apache Shiro as a security framework. Passwords are SHA1 hashed (no salt, no iterations). Login is SSL secured. However, the remaining part of the application is not SSL secured. In this context (no SSL) there should be a form where a user can change the password.
Since it wouldn't be a good idea to transmit it plainly it should be hashed on the client and then transmitted to the server. As the client is GWT (2.3) based, I am trying this library http://code.google.com/p/gwt-crypto, which uses code from bouncycastle.
However, in many cases (not all) the hashes generated by both frameworks differ in 1-4(?) characters.
For instance "happa3" is hashed to
"fe7f3cffd8a5f0512a5f1120f1369f48cd6f47c2"
by both implementations, whereas just "happa" is hashed to
"fb3c3a741b4e07a87d9cb68f3db020d6fbfed00a"
by the Shiro implementation and to
"fb3c3a741b4e07a87d9cb63f3db020d6fbfed00a"
by the gwt-crypto implementation (23rd character differs).
I wonder whether there is a "correct"/standard SHA1 hashing and whether there is a bug in one of the libraries or maybe my usage of them is flawed.
One of my first thoughts was related to different encodings or strange conversions due to different transport mechanisms (RPC vs. Post). To my knowledge though (and what puzzles me most), SHA1 hashes should differ completely with a high probability if there is just a difference of a single bit. So different encodings shouldn't be the issue here.
I am using this code on the client (GWT) for hashing:
String hashed = toHex(createSHA1Hash("password"));
...
private String createSHA1Hash(String passwordString){
SHA1Digest sha1 = new SHA1Digest();
byte[] bytes;
byte[] result = new byte[sha1.getDigestSize()];
try {
bytes = passwordString.getBytes();
sha1.update(bytes, 0, bytes.length);
int val = sha1.doFinal(result, 0);
} catch (UnsupportedEncodingException e) {}
return new String(result);
}
public String toHex(String arg) {
return new BigInteger(1, arg.getBytes()).toString(16);
}
And this on the server (Shiro):
String hashed = new Sha1Hash("password").toHex()
which afaics does something very similar behind the scenes (had a quick view on the source code).
Did I miss something obvious here?
EDIT: Seems like the GWT code does not run natively for some reason (i.e. just in development mode) and silently fails (it does compile, though). Have to find out why...
Edit(2): "int val = sha1.doFinal(result, 0);" is the line that makes trouble, i.e. if present, the whole code does not run natively (JS) but only in dev-mode (with wrong results)
You could test this version:
public class SHA1 {
public static native String calcSHA1(String s) /*-{
//
// A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined
// in FIPS 180-1
// Version 2.2 Copyright Paul Johnston 2000 - 2009.
// Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
// Distributed under the BSD License
// See http://pajhome.org.uk/crypt/md5 for details.
//
//
// Configurable variables. You may need to tweak these to be compatible with
// the server-side, but the defaults work in most cases.
//
var hexcase = 0; // hex output format. 0 - lowercase; 1 - uppercase
var b64pad = ""; // base-64 pad character. "=" for strict RFC compliance
//
// These are the functions you'll usually want to call
// They take string arguments and return either hex or base-64 encoded strings
//
function b64_sha1(s) { return rstr2b64(rstr_sha1(str2rstr_utf8(s))); }
function any_sha1(s, e) { return rstr2any(rstr_sha1(str2rstr_utf8(s)), e); }
function hex_hmac_sha1(k, d)
{ return rstr2hex(rstr_hmac_sha1(str2rstr_utf8(k), str2rstr_utf8(d))); }
function b64_hmac_sha1(k, d)
{ return rstr2b64(rstr_hmac_sha1(str2rstr_utf8(k), str2rstr_utf8(d))); }
function any_hmac_sha1(k, d, e)
{ return rstr2any(rstr_hmac_sha1(str2rstr_utf8(k), str2rstr_utf8(d)), e); }
//
// Perform a simple self-test to see if the VM is working
//
function sha1_vm_test()
{
return hex_sha1("abc").toLowerCase() == "a9993e364706816aba3e25717850c26c9cd0d89d";
}
//
// Calculate the SHA1 of a raw string
//
function rstr_sha1(s)
{
return binb2rstr(binb_sha1(rstr2binb(s), s.length * 8));
}
//
// Calculate the HMAC-SHA1 of a key and some data (raw strings)
//
function rstr_hmac_sha1(key, data)
{
var bkey = rstr2binb(key);
if(bkey.length > 16) bkey = binb_sha1(bkey, key.length * 8);
var ipad = Array(16), opad = Array(16);
for(var i = 0; i < 16; i++)
{
ipad[i] = bkey[i] ^ 0x36363636;
opad[i] = bkey[i] ^ 0x5C5C5C5C;
}
var hash = binb_sha1(ipad.concat(rstr2binb(data)), 512 + data.length * 8);
return binb2rstr(binb_sha1(opad.concat(hash), 512 + 160));
}
//
// Convert a raw string to a hex string
//
function rstr2hex(input)
{
try { hexcase } catch(e) { hexcase=0; }
var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
var output = "";
var x;
for(var i = 0; i < input.length; i++)
{
x = input.charCodeAt(i);
output += hex_tab.charAt((x >>> 4) & 0x0F)
+ hex_tab.charAt( x & 0x0F);
}
return output;
}
//
// Convert a raw string to a base-64 string
//
function rstr2b64(input)
{
try { b64pad } catch(e) { b64pad=''; }
var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var output = "";
var len = input.length;
for(var i = 0; i < len; i += 3)
{
var triplet = (input.charCodeAt(i) << 16)
| (i + 1 < len ? input.charCodeAt(i+1) << 8 : 0)
| (i + 2 < len ? input.charCodeAt(i+2) : 0);
for(var j = 0; j < 4; j++)
{
if(i * 8 + j * 6 > input.length * 8) output += b64pad;
else output += tab.charAt((triplet >>> 6*(3-j)) & 0x3F);
}
}
return output;
}
//
// Convert a raw string to an arbitrary string encoding
//
function rstr2any(input, encoding)
{
var divisor = encoding.length;
var remainders = Array();
var i, q, x, quotient;
// Convert to an array of 16-bit big-endian values, forming the dividend
var dividend = Array(Math.ceil(input.length / 2));
for(i = 0; i < dividend.length; i++)
{
dividend[i] = (input.charCodeAt(i * 2) << 8) | input.charCodeAt(i * 2 + 1);
}
//
// Repeatedly perform a long division. The binary array forms the dividend,
// the length of the encoding is the divisor. Once computed, the quotient
// forms the dividend for the next step. We stop when the dividend is zero.
// All remainders are stored for later use.
//
while(dividend.length > 0)
{
quotient = Array();
x = 0;
for(i = 0; i < dividend.length; i++)
{
x = (x << 16) + dividend[i];
q = Math.floor(x / divisor);
x -= q * divisor;
if(quotient.length > 0 || q > 0)
quotient[quotient.length] = q;
}
remainders[remainders.length] = x;
dividend = quotient;
}
// Convert the remainders to the output string
var output = "";
for(i = remainders.length - 1; i >= 0; i--)
output += encoding.charAt(remainders[i]);
// Append leading zero equivalents
var full_length = Math.ceil(input.length * 8 /
(Math.log(encoding.length) / Math.log(2)))
for(i = output.length; i < full_length; i++)
output = encoding[0] + output;
return output;
}
//
// Encode a string as utf-8.
// For efficiency, this assumes the input is valid utf-16.
//
function str2rstr_utf8(input)
{
var output = "";
var i = -1;
var x, y;
while(++i < input.length)
{
// Decode utf-16 surrogate pairs
x = input.charCodeAt(i);
y = i + 1 < input.length ? input.charCodeAt(i + 1) : 0;
if(0xD800 <= x && x <= 0xDBFF && 0xDC00 <= y && y <= 0xDFFF)
{
x = 0x10000 + ((x & 0x03FF) << 10) + (y & 0x03FF);
i++;
}
// Encode output as utf-8
if(x <= 0x7F)
output += String.fromCharCode(x);
else if(x <= 0x7FF)
output += String.fromCharCode(0xC0 | ((x >>> 6 ) & 0x1F),
0x80 | ( x & 0x3F));
else if(x <= 0xFFFF)
output += String.fromCharCode(0xE0 | ((x >>> 12) & 0x0F),
0x80 | ((x >>> 6 ) & 0x3F),
0x80 | ( x & 0x3F));
else if(x <= 0x1FFFFF)
output += String.fromCharCode(0xF0 | ((x >>> 18) & 0x07),
0x80 | ((x >>> 12) & 0x3F),
0x80 | ((x >>> 6 ) & 0x3F),
0x80 | ( x & 0x3F));
}
return output;
}
//
// Encode a string as utf-16
//
function str2rstr_utf16le(input)
{
var output = "";
for(var i = 0; i < input.length; i++)
output += String.fromCharCode( input.charCodeAt(i) & 0xFF,
(input.charCodeAt(i) >>> 8) & 0xFF);
return output;
}
function str2rstr_utf16be(input)
{
var output = "";
for(var i = 0; i < input.length; i++)
output += String.fromCharCode((input.charCodeAt(i) >>> 8) & 0xFF,
input.charCodeAt(i) & 0xFF);
return output;
}
//
// Convert a raw string to an array of big-endian words
// Characters >255 have their high-byte silently ignored.
//
function rstr2binb(input)
{
var output = Array(input.length >> 2);
for(var i = 0; i < output.length; i++)
output[i] = 0;
for(var i = 0; i < input.length * 8; i += 8)
output[i>>5] |= (input.charCodeAt(i / 8) & 0xFF) << (24 - i % 32);
return output;
}
//
// Convert an array of big-endian words to a string
//
function binb2rstr(input)
{
var output = "";
for(var i = 0; i < input.length * 32; i += 8)
output += String.fromCharCode((input[i>>5] >>> (24 - i % 32)) & 0xFF);
return output;
}
//
// Calculate the SHA-1 of an array of big-endian words, and a bit length
//
function binb_sha1(x, len)
{
// append padding
x[len >> 5] |= 0x80 << (24 - len % 32);
x[((len + 64 >> 9) << 4) + 15] = len;
var w = Array(80);
var a = 1732584193;
var b = -271733879;
var c = -1732584194;
var d = 271733878;
var e = -1009589776;
for(var i = 0; i < x.length; i += 16)
{
var olda = a;
var oldb = b;
var oldc = c;
var oldd = d;
var olde = e;
for(var j = 0; j < 80; j++)
{
if(j < 16) w[j] = x[i + j];
else w[j] = bit_rol(w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16], 1);
var t = safe_add(safe_add(bit_rol(a, 5), sha1_ft(j, b, c, d)),
safe_add(safe_add(e, w[j]), sha1_kt(j)));
e = d;
d = c;
c = bit_rol(b, 30);
b = a;
a = t;
}
a = safe_add(a, olda);
b = safe_add(b, oldb);
c = safe_add(c, oldc);
d = safe_add(d, oldd);
e = safe_add(e, olde);
}
return Array(a, b, c, d, e);
}
//
// Perform the appropriate triplet combination function for the current
// iteration
//
function sha1_ft(t, b, c, d)
{
if(t < 20) return (b & c) | ((~b) & d);
if(t < 40) return b ^ c ^ d;
if(t < 60) return (b & c) | (b & d) | (c & d);
return b ^ c ^ d;
}
//
// Determine the appropriate additive constant for the current iteration
//
function sha1_kt(t)
{
return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 :
(t < 60) ? -1894007588 : -899497514;
}
//
// Add integers, wrapping at 2^32. This uses 16-bit operations internally
// to work around bugs in some JS interpreters.
//
function safe_add(x, y)
{
var lsw = (x & 0xFFFF) + (y & 0xFFFF);
var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
return (msw << 16) | (lsw & 0xFFFF);
}
//
// Bitwise rotate a 32-bit number to the left.
//
function bit_rol(num, cnt)
{
return (num << cnt) | (num >>> (32 - cnt));
}
return rstr2hex(rstr_sha1(str2rstr_utf8(s)));
}-*/;
}
I'm using it in my client side sha generation and it worked well.

form a number using consecutive numbers

I was puzzled with one of the question in Microsoft interview which is as given below:
A function should accept a range( 3 - 21 ) and it should print all the consecutive numbers combinations to form each number as given below:
3 = 1+2
5 = 2+3
6 = 1+2+3
7 = 3+4
9 = 4+5
10 = 1+2+3+4
11 = 5+6
12 = 3+4+5
13 = 6+7
14 = 2+3+4+5
15 = 1+2+3+4+5
17 = 8+9
18 = 5+6+7
19 = 9+10
20 = 2+3+4+5+6
21 = 10+11
21 = 1+2+3+4+5+6
could you please help me in forming this sequence in C#?
Thanks,
Mahesh
So here is a straightforward/naive answer (in C++, and not tested; but you should be able to translate). It uses the fact that
1 + 2 + ... + n = n(n+1)/2,
which you have probably seen before. There are lots of easy optimisations that can be made here which I have omitted for clarity.
void WriteAsSums (int n)
{
for (int i = 0; i < n; i++)
{
for (int j = i; j < n; j++)
{
if (n = (j * (j+1) - i * (i+1))/2) // then n = (i+1) + (i+2) + ... + (j-1) + j
{
std::cout << n << " = ";
for (int k = i + 1; k <= j; k++)
{
std::cout << k;
if (k != j) // this is not the interesting bit
std::cout << std::endl;
else
std::cout << " + ";
}
}
}
}
}
This is some pseudo code to find all the combinations if any exists:
function consecutive_numbers(n, m)
list = [] // empty list
list.push_back(m)
while m != n
if m > n
first = list.remove_first
m -= first
else
last = list.last_element
if last <= 1
return []
end
list.push_back(last - 1)
m += last - 1
end
end
return list
end
function all_consecutive_numbers(n)
m = n / 2 + 1
a = consecutive_numbers(n, m)
while a != []
print_combination(n, a)
m = a.first - 1
a = consecutive_numbers(n, m)
end
end
function print_combination(n, a)
print(n + " = ")
print(a.remove_first)
foreach element in a
print(" + " + element)
end
print("\n")
end
A call to all_consecutive_numbers(21) would print:
21 = 11 + 10
21 = 8 + 7 + 6
21 = 6 + 5 + 4 + 3 + 2 + 1
I tested it in ruby (code here) and it seems to work. I'm sure the basic idea could easily be implemented in C# as well.
I like this problem. Here is a slick and slightly mysterious O(n) solution:
void DisplaySum (int n, int a, int b)
{
std::cout << n << " = ";
for (int i = a; i < b; i++) std::cout << i << " + ";
std::cout << b;
}
void WriteAsSums (int n)
{
N = 2*n;
for (int i = 1; i < N; i++)
{
if (~(N%i))
{
int j = N/i;
if (j+i%2)
{
int a = (j+i-1)/2;
int b = (j-i+1)/2;
if (a>0 & a<b) // exclude trivial & negative solutions
DisplaySum(n,a,b);
}
}
}
}
Here's something in Groovy, you should be able to understand what's going on. It's not the most efficient code and doesn't create the answers in the order you cite in your question (you seem to be missing some though) but it might give you a start.
def f(a,b) {
for (i in a..b) {
for (j in 1..i/2) {
def (sum, str, k) = [ 0, "", j ]
while (sum < i) {
sum += k
str += "+$k"
k++
}
if (sum == i) println "$i=${str[1..-1]}"
}
}
}
Output for f(3,21) is:
3=1+2
5=2+3
6=1+2+3
7=3+4
9=2+3+4
9=4+5
10=1+2+3+4
11=5+6
12=3+4+5
13=6+7
14=2+3+4+5
15=1+2+3+4+5
15=4+5+6
15=7+8
17=8+9
18=3+4+5+6
18=5+6+7
19=9+10
20=2+3+4+5+6
21=1+2+3+4+5+6
21=6+7+8
21=10+11
Hope this helps. It kind of conforms to the tenet of doing the simplest thing that could possibly work.
if we slice a into 2 digit, then a = b + (b+1) = 2*b + (0+1)
if we slice a into 3 digit, then a = b + (b+1) + (b+2) = 3*b + (0+1+2)
...
if we slice a into n digit, then a = b + (b+1) +...+ (b+n) = nb + (0+1+n-1)
the last result is a = nb + n*(n-1)/2, a,b,n are all ints.
so O(N) Algorithm is:
void seq_sum(int a)
{
// start from 2 digits
int n=2;
while(1)
{
int value = a-n*(n-1)/2;
if(value < 0)
break;
// meet the quotation we deduct
if( value%n == 0 )
{
int b=value/n;
// omit the print stage
print("......");
}
n++;
}
}