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URL: https://www.javascriptbank.com/word-combinations.html
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Phiên bản đầy đủ: jsB@nk » Linh tinh » Kết hợp từ
URL: https://www.javascriptbank.com/word-combinations.html
<script language="javascript">// Created by: Brett McLean :: http://www.brettbits.com/// calculateCombinations takes inputText as a parameter, which is a string containing all// user-provided characters. It calculates how many combinations exist for these characters,// prints them in the outputField, as well as returning the number to the calling function.function calculateCombinations(inputText) { inputCopy = inputText; numerator = factorial(inputText.length); denominator = 1; while(inputCopy != "") { denominator *= factorial(howManyOccurances(inputCopy, inputCopy.charAt(0))); inputCopy = stripCharactersFromString(inputCopy, inputCopy.charAt(0)); } document.combform.outputField.value = (numerator/denominator); return numerator/denominator;}// HowManyOccurances returns how many times characterToFind appears in stringToSearch.// Example: howManyOccurances("abcabcabca", "a") returns 4.function howManyOccurances(stringToSearch, characterToFind) { count = 0; for(i = 0; i < stringToSearch.length; i++) { if(stringToSearch.charAt(i) == characterToFind) count++; } return count;}// stripCharactersFromString returns stringToStripFrom, with all occurances// of characterToStrip removed.// Example: stripCharactersFromString("abcabcabca", "a") returns "bcbcbc".function stripCharactersFromString(stringToStripFrom, characterToStrip) { outputString = ""; for(i = 0; i < stringToStripFrom.length; i++) if(stringToStripFrom.charAt(i) != characterToStrip) outputString += stringToStripFrom.charAt(i); return outputString;}// factorial returns the factorial of inputNumber, also written as (inputNumber)!.// Definition of factorial: inputNumber! = (inputNumber) * (inputNumber-1) * ... * 2 * 1// Example: factorial(4) = 4! = 4 * 3 * 2 * 1 = 24function factorial(inputNumber) { outputNumber = 1; for(i = inputNumber; i > 0; i--) outputNumber *= i; return outputNumber;}// createWordList recursively generates an array containing all possible combinations of// a given string of letters. It solves this problem by taking each letter in the word,// and then appending to it all possible combinations of the remaining letters.// Initially, wordArray should be empty, strbase should equal "", and remainingchars// should contain the user's input string.function createWordList(wordArray, strbase, remainingchars) {if(remainingchars.length == 1) { // base case: only one character remains, and can be arranged only one way wordArray[wordArray.length] = strbase + remainingchars.charAt(0); // append one remaining character to string base} else { for(var j = 0; j < remainingchars.length; j++) { currchar = remainingchars.charAt(j); // first character of remaining characters if(remainingchars.indexOf(currchar) == j) // ensures repeat letters do not cause combination redundancy wordArray = createWordList(wordArray, strbase + remainingchars.charAt(j), remainingchars.substring(0, j) + remainingchars.substring(j+1, remainingchars.length)); //recursive call }} return wordArray; //returns the wordArray containing stbase plus all possible combinations of remainingchars}// printWordList accepts an array, and prints each string contained within, separated by commas.// It then places this output into the textarea named "combinationlist".function printWordList(wordArray) { output = ""; for(i = 0; i < wordArray.length-1; i++) output += wordArray[i] + ", "; output += wordArray[wordArray.length-1]; document.combform.combinationlist.value = output;}// showCombinations receives the user's input characters as a parameter, calculates how many combinations exist from these// characters, and then displays every one of these combinations. This function has a safeguard in which it warns// the user if a calculation will take a long time to process.function showCombinations(inputText) { numCombinations = calculateCombinations(inputText); confirmMessage = "The following calculation will involve finding " + numCombinations + " different combinations of the letters"; confirmMessage += "\nyou have provided. Depending on the speed of your computer, it may take a while to"; confirmMessage += "\nprocess this request, or in a worst-case scenario, your web browser may crash."; confirmMessage += "\nThis will do no damage to your computer that a restart will not solve."; confirmMessage += "\nAre you sure you want to continue?"; if(numCombinations < 5000 || confirm(confirmMessage)) // only do it if the number of combinations to calculate is low, or the user agrees to the warning printWordList(createWordList(new Array(), "", inputText)); // calculate and then print all combinations of the letters provided}</script><!-- This script downloaded from www.JavaScriptBank.com Come to view and download over 2000+ free javascript at www.JavaScriptBank.com--><table align="center"> <form name="combform" onSubmit="calculateCombinations(inputField.value); return false;"> <tr><td> Enter letters here: <input type="text" name="inputField"> </td></tr> <tr><td> <input type="submit" value="How Many Combinations Are There?"> </td></tr> <tr><td> Your letters can be arranged <input type="text" name="outputField" size=10> unique ways. </td></tr> <tr><td> <textarea name="combinationlist" rows=10 cols=70>List of character combinations are displayed here.</textarea> </td></tr> <tr><td> <input type="button" onclick="showCombinations(inputField.value);" value="List All Possible Combinations"> </td></tr> </form></table><!-- This script downloaded from www.JavaScriptBank.com Come to view and download over 2000+ free javascript at www.JavaScriptBank.com-->