题解 | #DNA序列#

#include<bits/stdc++.h>
using namespace std;
vector<string> vec;
int main()
{
    string str;
    int n;
    cin >> str >> n;
    for(int i=0;i<str.length()-n+1;i++)
    {
        int j = i;
        string substr = str.substr(j,n);
        vec.push_back(substr);
    }
    double max = -1.0;
    vector<string>::iterator cur;
    for(vector<string>::iterator it = vec.begin(); it != vec.end(); it++)
    {
        double gets = 0.0;
        double gc_ratio = 0.0;
        string sit = *it;
        for(int i = 0; i < sit.length(); i++)
        {
            if(sit[i] == 'C' || sit[i] == 'G')
            {
                gets ++;
            }
        }
        gc_ratio = gets / n;
        if(gc_ratio > max)
        {
            max = gc_ratio;
            cur = it;
        }
    }
    cout << *cur;
    return 0;
}