Given a collection of numbers, return all possible permutations.
For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].
https://leetcode.com/problems/permutations/
数字排列。
循环每一位数字，每个数都和所有数交换（包括自己）。
1 /** 2 * @param {number[]} nums 3 * @return {number[][]} 4 */ 5 var permute = function(nums) { 6 var result = []; 7 getPermute(0); 8 return result; 9 10 function getPermute(index){ 11 if(index === nums.length){ 12 result.push(nums.slice(0)); 13 return; 14 } 15 for(var i = index; i < nums.length; i++){ 16 switchNum(i, index); 17 getPermute(index + 1); 18 switchNum(i, index); 19 } 20 } 21 function switchNum(i, j){ 22 var tmp = nums[i]; 23 nums[i] = nums[j]; 24 nums[j] = tmp; 25 } 26 };
原文：http://www.cnblogs.com/Liok3187/p/4986918.html