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CodeForces 472A Design Tutoria

[编程题]CodeForces 472A Design Tutoria

热度指数：16 时间限制：C/C++ 1秒，其他语言2秒空间限制：C/C++ 256M，其他语言512M
算法知识视频讲解

One way to create a task is to learn from math. You can generate some random math statement or modify some theorems to get something new and build a new task from that.

For example, there is a statement called the "Goldbach's conjecture". It says: "each even number no less than four can be expressed as the sum of two primes". Let's modify it. How about a statement like that: "each integer no less than 12 can be expressed as the sum of two composite numbers." Not like the Goldbach's conjecture, I can prove this theorem.

You are given an integer n no less than 12, express it as a sum of two composite numbers.

输入描述:

The only line contains an integer n(12 ≤ n ≤ 10⁶).

输出描述:

Output two composite integers x and y(1 < x, y < n) such that x + y = n. If there are multiple solutions, you can output any of them.

示例1

输入

12<br />15<br />23<br />1000000<br />

输出

4 8<br />6 9<br />8 15<br />500000 500000<br />

备注:

In the first example, 12 = 4 + 8 and both 4, 8 are composite numbers. You can output "6 6" or "8 4" as well.

In the second example, 15 = 6 + 9. Note that you can't output "1 14" because 1 is not a composite number.

算法知识视频讲解

martinc

#include<iostream>
#include<math.h>
using namespace std;
bool isPrime(int n){
    for(int i=2;i<=sqrt(n);i++){
        if(n%i==0){
            return false;
            break;
        }
    }
    return true;
}
int main(){
    int nums;
    while(cin>>nums){
        for(int i=4;i<=nums/2;i++){
            if(!isPrime(i)&&!isPrime(nums-i)){
                cout<<i<<" "<<nums-i<<endl;
                break;
            }
        }
    }
    return 0;
}

发表于 2019-07-21 19:51:13 回复(0)