给定一个没有重复数字的序列，返回其所有可能的全排列。
示例:
输入: [1,2,3]
输出:
[
[1,2,3],
[1,3,2],
[2,1,3],
[2,3,1],
[3,1,2],
[3,2,1]
]
代码
class Solution {
public:
vector<vector<int> > permute(vector<int> &num) {
vector<vector<int> > res;
permuteDFS(num, 0, res);
return res;
}
void permuteDFS(vector<int> &num, int start, vector<vector<int> > &res) {
if (start >= num.size()) res.push_back(num);
for (int i = start; i < num.size(); ++i) {
swap(num[start], num[i]);
permuteDFS(num, start + 1, res);
swap(num[start], num[i]);
}
}
};
