LeetCode: 46. Permutations

题目描述

Given a collection of distinct 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],  [3,2,1]]

题目大意就是让我们把给定数组的所有数字全排列列举出来。

解题思路

直接暴力搜索就 OK。

AC代码

class Solution {public:    void permute(vector<vector<int>>& ans, vector<int>& nums, vector<int>& now)    {        if(now.size() == nums.size())        {            ans.push_back(now);            return;        }        for(int i = 0; i < nums.size(); ++i)        {            if(nums[i] != INT_MAX)            {                // 用过的数字标记为INT_MAX                now.push_back(nums[i]);                nums[i] = INT_MAX;                permute(ans, nums, now);                // 取消标记                nums[i] = now.back();                now.pop_back();            }        }    }    vector<vector<int>> permute(vector<int>& nums) {        vector<vector<int>> ans;        vector<int> now;        permute(ans, nums, now);        return ans;    }};