算法训练 字串统计

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <stdlib.h>
#include <cstdlib>
#include <string.h>
#include <string>
#include <cmath>
#include <map>
using namespace std;
int n;
string s;
map<string, int> mymap;//记录出现次数
map<string, int> mymap2;//记录次序
int main() {
    scanf("%d", &n);
    cin >> s;
    int len = s.length();
    int index = 0;
    string max_string;
    int max_sum = 0;
    for (int i = n; i <= len; i++) {
        for (int j = 0; j + i <= len; j++) {
            string t = s.substr(j, i);
            mymap[t]++;
            //cout <<t<<" "<<mymap[t] << endl;
            mymap2[t] = index++;
            if (mymap[t] > max_sum) {//如果次数最大
                max_sum = mymap[t];
                max_string = t;
            }
            else if (mymap[t] == max_sum) {//次数相同 
                if (max_string.length() < t.length()) {//第一比长度
                    max_string = t;
                }
                else if (max_string.length() == t.length() && mymap2[t] < mymap2[max_string]) {//相同长度比 先后
                    max_string = t;
                }
            }
        }
    }
    cout << max_string;
    return 0;
}