HUST 1541 解方程

 参考自：https://www.cnblogs.com/ECJTUACM-873284962/p/6394836.html

1541 - Student’s question

时间限制：1秒 内存限制：128兆

题目描述

    YY is a student. He is tired of calculating the quadratic equation. He wants you to help him to get the result of the quadratic equation. The quadratic equation’ format is as follows: ax^2+bx+c=0.

输入

       The first line contains a single positive integer N, indicating the number of datasets. The next N lines are n datasets. Every line contains three integers indicating integer numbers a,b,c (a≠0).

输出

       For every dataset you should output the result in a single line. If there are two same results, you should just output once. If there are two different results, you should output them separated by a space. Be sure the later is larger than the former. Output the result to 2 decimal places. If there is no solution, output “NO”.

 

 

输入　

3

1 2 1

1 2 3

1 -9 6

输出

-1.00

NO

0.73 8.27

解法：

 

#include <bits/stdc++.h>
using namespace std;
int main()
{
    double n,a,b,c;
    while(cin>>n)
    {
        while(n--)
        {
            cin>>a>>b>>c;
            if(a==0)break;
            else
            {
            if(b*b-4*a*c>=0)
            {
                double t1=(-b)/a;
                double t2=c/a;
                double t3=sqrt(t1*t1-4*t2);
                double x1=(t1+t3)/2;
                double x2=(t1-t3)/2;
                if(x1==x2) cout<<fixed<<setprecision(2)<<x1<<endl;
                else if(x1<x2)
                cout<<fixed<<setprecision(2)<<x1<<" "<<x2<<endl;
                else if(x1>x2)
                    cout<<fixed<<setprecision(2)<<x2<<" "<<x1<<endl;
            }
            else cout<<"NO"<<endl;
            }
        }
    }
    return 0;
}