Jam's math problem（HDU5615）

Jam's math problem

Problem Description

Jam has a math problem. He just learned factorization.
He is trying to factorize ax2+bx+c into the form of pqx2+(qk+mp)x+km=(px+k)(qx+m).
He could only solve the problem in which p,q,m,k are positive numbers.
Please help him determine whether the expression could be factorized with p,q,m,k being postive.

 

Input

The first line is a number T, means there are T(1≤T≤100) cases

Each case has one line,the line has 3 numbers a,b,c(1≤a,b,c≤100000000)

 

Output

You should output the "YES" or "NO".

 

Sample Input

21 6 51 6 4

 

Sample Output

YESNO

题意：方程的因式分解，十字相乘，例如x^2+6*x+5=(x+1)(x+5)，这样就可以分解，可以通过Δ=b²-4ac进行判定，首先Δ得大于0，然后Δ=为完全平方数就可以分解，此处只需记住。。。。。。。。。。。。。。。。。
代码：
#include<stdio.h>
#include<math.h>
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        long long int a,b,c,d,e;
        scanf("%lld%lld%lld",&a,&b,&c);
        d=b*b-4*a*c;  //Δ小于0直接输出NO，因为这样就没解
        if(d<0)printf("NO\n");
        else
        {
            e=sqrt(d);    
            if(e*e==d)printf("YES\n");     //为完全平方数就输出YES
            else printf("NO\n");
        }
    }
}