题解 | #DNA序列#

#include <iostream>
using namespace std;

int main() {
    string to_test;
    getline(cin, to_test);
    double len  = 0;
    cin >> len;
    double rai = -1;
    double num = 0;
    int l = 0;
    int r = 0;
    for(int i = 0, j = len - 1; j < to_test.size(); i++, j++) {
        num = 0;
        for(int k = i; k <= j; k++) {
            if(to_test[k] == 'C' || to_test[k] == 'G') {
                num++;
            }
        }
        if((num / len) > rai) { // 浮点数除法
            rai = num / len; // 浮点数除法
            l = i;
            r = j;
        }
    }
    cout << to_test.substr(l, len) << endl;
    return 0;
}

注意浮点数除法，可能会出现用整数除得零的情况