题目：

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代码（首刷自解 2024年2月6日）：

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

        for (int i = 0; i < nums.size(); ++i) {
            if (used[i] == true) continue;
            path.push_back(nums[i]);
            used[i] = true;
            backtracking(nums, depth + 1, used);
            used[i] = false;
            path.pop_back();
        }
        return;
    }
    vector<vector<int>> permute(vector<int>& nums) {
        res.clear();
        path.clear();
        vector<bool> used(nums.size(), 0);//记录同一树枝上已用过的节点
        backtracking(nums, 0 ,used);
        return res;
    }
};