LeetCode-46. Permutations

Given a collection of distinct integers, return all possible permutations.

Example:

Input: [1,2,3]
Output:
[
  [1,2,3],
  [1,3,2],
  [2,1,3],
  [2,3,1],
  [3,1,2],
  [3,2,1]
]

题解：

class Solution {
public:
  void bfs(vector<int> nums, vector<bool> visit, int n, vector<int> idx, int d, vector<vector<int>> &ans) {
    for (int i = 0; i < n; i++) {
      if (visit[i] == false) {
        visit[i] = true;
        idx.push_back(nums[i]);
        if (d == n - 1) {
          ans.push_back(idx);
        }
        else {
          bfs(nums, visit, n, idx, d + 1, ans);
        }
        visit[i] = false;
        idx.pop_back();
      }
    }
  }
  vector<vector<int>> permute(vector<int>& nums) {
    vector<vector<int>> ans;
    int n = nums.size();
    vector<bool> visit(n + 1, 0);
    vector<int> idx;
    bfs(nums, visit, n, idx, 0, ans);
    return ans;
  }
};