题解 | #有重复项数字的全排列#

#include <algorithm>
#include <vector>
class Solution {
  private:
    vector<vector<int>> res;
    vector<int> path;
  public:
    void backTrack(vector<int>& num, vector<bool>& used) {
        if (path.size() == num.size()) {
            res.push_back(path);
            return;
        }
        for (int i = 0; i < num.size(); i++) {
            if (used[i]) {
                continue;
            }
            if (i > 0 && num[i] == num[i - 1] && !used[i - 1]) {
                continue;
            }
            used[i] = true;
            path.push_back(num[i]);
            backTrack(num, used);
            used[i] = false;
            path.pop_back();
        }
    }
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param num int整型vector
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > permuteUnique(vector<int>& num) {
        // write code here
        vector<bool> used(num.size(), false);
        std::sort(num.begin(), num.end());
        backTrack(num, used);
        return res;
    }
};