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Problem Description Patrick Star find an oval.
The half of longer axes is on the x-axis with length a .
The half of shorter axes is on the y-axis with length b .
Patrick Star plan to choose a real number c randomly from [0,b] , after that, Patrick Star will get a rectangle :
1. The four vertexes of it are on the outline of the oval.
2. The two sides of it parallel to coordinate axis.
3. One of its side is y=c .
Patrick Star want to know the expectations of the rectangle's perimeter. Input The first line contain a integer T (no morn than 10), the following is T test case, for each test case :
Each line contains contains two integer a, b (0<b<a<105 ). Separated by an white space.
Output For each test case output one line denotes the expectations of the rectangle's perimeter .
You should keep exactly 6 decimal digits and ignore the remain decimal digits.
It is guaranted that the 7-th decimal digit of answer wont be 0 or 9. Sample Input 1 2 1 Sample Output 8.283185 |
题意：给你一个椭圆并且告诉你他的长轴a和短轴b的值，接着有一条直线y=c与椭圆相交，以此确定四个点，需要你求以这四个点为顶点的矩形的周长的期望。
#include <cstdio>
#include <cmath>
#include <iostream>
#define PI acos(-1)
using namespace std;
int main() {
int t, a, b;
scanf("%d", &t);
while(t--) {
scanf("%d %d", &a, &b);
double ans = PI*a + 2*b;
ans -= 0.0000005;
printf("%lf\n", ans);
}
return 0;
}