题解 | #字符串出现次数的TopK问题# map和cmp的联合使用

class Solution {
public:
    /**
     * return topK string
     * @param strings string字符串vector strings
     * @param k int整型 the k
     * @return string字符串vector<vector<>>
     */
    /*
        map<string, int>
        priorty<int, string>
        vector<>
    */
    static bool cmp(vector<string> &a, vector<string> &b) {
        if (a[1] == b[1]) {
            return a[0] < b[0];
        }
        return stoi(a[1]) > stoi(b[1]);
    }
    vector<vector<string> > topKstrings(vector<string>& strings, int k) {
        // write code here
        int len = strings.size();
        map<string, int>mp;
        // 1, 将数据记录到map中
        for (int i = 0; i < len; i++) {
            mp[strings[i]]++;
        }
        
        map<string, int>::iterator it = mp.begin();
        vector<vector<string>> ret;
        // 2， 将数据记录到vector中
        for (; it != mp.end(); it++) {
            ret.push_back({it->first, to_string(it->second)});
        }
        // 3，比较
        sort(ret.begin(), ret.end(), cmp);
        
        ret.resize(k);
        return ret;
    }
};