题解 | #DNA序列#

#include <iostream>
#include <string>
using namespace std;

int main() {
    string str;
    int n;
    cin >> str >> n;
    int maxNum = 0;
    string ans;
    for(int i = 0; i <= str.length() - n; i++){
        string subStr = str.substr(i, n);
        int num = 0;
        for(int j = 0; j < n; j++){
            if(subStr[j] == 'G' || subStr[j] == 'C') num++;
        }
        if(num > maxNum){
            ans = subStr;
            maxNum = num;
        }
    }
    cout << ans << endl;
    return 0;
}