[JAVASCRIPT] Permutation 递归算法以及结果筛选

来源：互联网发布：淘宝助理发布宝贝教程编辑：程序博客网时间：2024/06/04 19:50

function permAlone(str) {var arr = [];for(var index in str) {arr.push(str[index]);}//console.log(arr);var permutations = getPermutation(arr);for(var index in permutations) {var tamp = permutations[index].join("");permutations[index] = tamp;}permutations = getDifference(permutations);console.log(permutations);return permutations;}permAlone("aba");function getDifference(arr) {

                                 //去掉有连续两个项的

                                //console.log(/(.)\1/g.test("baa"));   // falsevar result = [];for(var i = 0; i < arr.length; i++) {if(!/(.)\1/g.test(arr[i])) {result.push(arr[i]);}}return result;}function getPermutation(arr) {if(arr.length == 1) {return [arr];}var permutation = [];for(var i = 0; i < arr.length; i++) {var firstEle = arr[i];var arrClone = arr.slice(0);arrClone.splice(i, 1);var childPermutation = getPermutation(arrClone);//递归 获得全排列 for(var j = 0; j < childPermutation.length; j++) {childPermutation[j].unshift(firstEle);}permutation = permutation.concat(childPermutation);}return permutation;}
递归的原理是：比如 “123”的全排列，可以看作 1+[23,32];2+[13,31];3+[12,21];  而“23”又可以看作 2+[3] ;3+[2];
所以递归的方式就是不断查找n-1 项的排列， 直到为1 ，返回其本身；

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