week_11_ Permutations

Description

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]]

Solution

结合vector数据结构的特性，递归遍历组合即可。

代码实现如下：

class Solution {public:    vector<vector<int> > permute(vector<int> &num) {    vector<vector<int> > result;        permuteRecursive(num, 0, result);    return result;    }       void permuteRecursive(vector<int> &num, int begin, vector<vector<int> > &result){if (begin >= num.size()) {    result.push_back(num);    return;}for (int i = begin; i < num.size(); i++) {    swap(num[begin], num[i]);    permuteRecursive(num, begin + 1, result);    swap(num[begin], num[i]);}    }};