力扣-回溯-46 全排列

思路

单层递归逻辑中用used数组记录是否用过就可以了

代码

class Solution {
public:
    vector<int> path;
    vector< vector<int> > result;
    void backtracking(vector<int> nums, vector<bool> used){
        if(path.size() == nums.size()){
            result.push_back(path);
            return;
        }

        for(int i = 0; i < nums.size(); i++){
            if(used[i]) continue;
            path.push_back(nums[i]);
            used[i] = true;
            backtracking(nums, used);
            used[i] = false;
            path.pop_back(); 
        }
        return;
    }

    vector<vector<int>> permute(vector<int>& nums) {
        path.clear();
        result.clear();
        vector<bool> used(nums.size(), false);
        backtracking(nums, used);
        return result;
    }
};