面试题 08.08. 有重复字符串的排列组合

面试题 08.08. 有重复字符串的排列组合 - 力扣（LeetCode）

回溯，去重：剑指 Offer 38. 字符串的排列_zj-CSDN博客

class Solution {
public:
    vector<string> res;
    string tmp;
    vector<string> permutation(string S) {
        sort(S.begin(), S.end());
        backtrack(S);
        return res;
    }
    void backtrack(string &s){
        if(tmp.size() == s.size()){
            res.emplace_back(tmp);
            return;
        }
        for(int i = 0; i < s.size(); ++i){
            if(s[i] == '_' || (i > 0 && s[i] == s[i-1]))    continue;
            char c = s[i];
            tmp += s[i];
            s[i] = '_';
            backtrack(s);
            s[i] = c;
            tmp.pop_back();
        }
    }
};