1152 Google Recruitment

多年不练截取string用substr都忘了，还有要记住最后是要输出整一条string，比如，应该0023，而不是23，一开始一直不对。。。


#include <iostream>
#include <stdlib.h>
#include <string>
#include<algorithm>
#include<vector>
#include<cmath>

using namespace std;

int isprime(int k) {
    int result = 0;
    if (k == 1) {
        result = 1;
    }

    for (int i = 2; i < sqrt(k); i++) {
        if (k%i == 0) {
            result = 1;
            break;
        }
    }
    return result;
}



int main() {

    int l, n;
    string s;
    cin >> l >> n;
    cin >> s;
    string result = "404";
    for (int i = 0; i < l - n + 1; i++) {
        string k = s.substr(i, n);
        int t = stoi(k);

        if (isprime(t) == 0) {
            result = k;
            break;
        }
    }
    cout << result;
    system("pause");
};