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：

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 int main()
 4 {
 5     double n,a,b,c;
 6     while(cin>>n)
 7     {
 8         while(n--)
 9         {
10             cin>>a>>b>>c;
11             if(a==0)break;
12             else
13             {
14             if(b*b-4*a*c>=0)
15             {
16                 double t1=(-b)/a;
17                 double t2=c/a;
18                 double t3=sqrt(t1*t1-4*t2);
19                 double x1=(t1+t3)/2;
20                 double x2=(t1-t3)/2;
21                 if(x1==x2) cout<<fixed<<setprecision(2)<<x1<<endl;
22                 else if(x1<x2)
23                 cout<<fixed<<setprecision(2)<<x1<<" "<<x2<<endl;
24                 else if(x1>x2)
25                     cout<<fixed<<setprecision(2)<<x2<<" "<<x1<<endl;
26             }
27             else cout<<"NO"<<endl;
28             }
29         }
30     }
31     return 0;
32 }