题解 | #DNA序列#

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

int main() {
    string str;
    cin >> str;
    int n;
    cin >> n;
    int j, sum;
    vector<char> s;
    float GCratio = 0, maxRatio = 0;
    for (int i = 0; i < str.size() - n + 1; i++) {
        j = 0;
        sum = 0;
        while (j < n) {
            if (str[i + j] == 'C' || str[i + j] == 'G') {
                sum++;
            }
            j++;
        }
        GCratio = (float)sum / n;
        if (maxRatio < GCratio) {
            maxRatio = GCratio;
            s.clear();
            for (int k = 0; k < n; k++) {
                s.push_back(str[i + k]);
            }
        }
    }
    for (int k = 0; k < n; k++) {
        cout << s[k];
    }
    return 0;
}