HJ99 自守数

自守数_牛客题霸_牛客网 (nowcoder.com)

#include <iostream>
#include<cmath>
using namespace std;
bool Ending_Same(int a)
{int a_a = a * a;if (a_a == a)return true;int i = 1;while (a_a != 0 && a_a/ (int)pow(10, i)!=0)//保证a*a有足够的位数{int end = a_a % (int)pow(10, i);//从后往前取，依次取1位，2位...if (end == a)return true;i++;}return false;
}
int main() {int n;cin >> n;int sum = 0;for (int i = 0; i <= n; i++){if (Ending_Same(i))sum++;}cout << sum;return 0;
}

OR86N 返回小于N的质数个数

 

#include <iostream>
using namespace std;
int Count(int a)
{if(a==0||a==1)return 0;if(a==2)return 1;int sum = 1;while(a>2){int i=2;for(i=2;i<a;i++){if(a%i == 0)break;}if(a==i)sum++;--a;}return sum;
}
int main() {int n;cin>>n;cout<<Count(n);return 0;
}