题解 | #DNA序列#

#include <bits/stdc++.h>

using namespace std;

void process(string str, int num, string& res){
    vector<string> vec; //保存所有可能的字串
    
    for(int i = 0; i < str.size() - num + 1; i++){
        string tmp = str.substr(i, num);
        //cout << tmp << endl;
        vec.push_back(tmp);
    }
    
    int maxLen = INT_MIN;
    for(string s : vec){
        int t = 0;
        for(char ch : s){
            if(ch == 'C' || ch == 'G'){
                t++; //当前字串中C和G的个数
            }
        }
        
        if(t > maxLen){
            res = s;
            maxLen = t;
        }
    }
}

int main(){
    string str = "";
    cin >> str;
    int n = 0;
    cin >> n;
    
    string res = "";
    process(str, n, res);
    
    cout << res << endl;
    
    return 0;
}