PTA甲級考試真題練習152——1152 Google Recruitment

題目

思路

注意看輸出的時候要輸出前面的0即可

代碼

#include <iostream>
#include <string>
#include <string.h>
using namespace std;
bool IsPrime(int num) {
	if (num <= 1)
		return false;
	int sqr = sqrt(1.0 * num);
	for (int i = 2; i < sqr; ++i) {
		if (num % i == 0)
			return false;
	}
	return true;
}
int main()
{
	int len, num;
	string s;
	cin >> len >> num >> s;
	for (int i = 0; i <= len - num; ++i) {
		string sub = s.substr(i,num);
		int n = stoi(sub);
    int cnt = sub.length();
		if (IsPrime(n)) {
      int tmp = n;
      while(tmp != 0){
        tmp /= 10;
        cnt--;
      }
			for(int j = 0;j<cnt;++j)
        cout<<0;
      cout<<n;
			return 0;
		}
	}
	cout << 404;
	return 0;
}