Problem Description
Now,given the equation 8*x^4 + 7*x^3 + 2*x^2 + 3*x + 6 == Y,can you find its solution between 0 and 100;
Now please try your lucky.
Input
The first line of the input contains an integer T(1<=T<=100) which means the number of test cases. Then T lines follow, each line has a real number Y (fabs(Y) <= 1e10);
Output
For each test case, you should just output one real number(accurate up to 4 decimal places),which is the solution of the equation,or “No solution!”,if there is no solution for the equation between 0 and 100.
Sample Input
2
100
-4
Sample Output
1.6152
No solution!
二分
#include <cstdio>
#include <cstring>
#include <map>
#include <string>
#include <iostream>
using namespace std;
const int MAX = 19;
int T, Y;
double func(double x)
{
return 8 * x * x * x * x + 7 * x * x * x + 2 * x * x
+ 3 * x + 6 ;
}
int main()
{
scanf("%d", &T);
while(T--)
{
scanf("%d", &Y);
double l, r, mid;
l = 0.0;
r = 100.0;
while( r - l > 1e-6)
{
mid = (l + r) / 2;
if(func(mid) < Y)
l = mid;
else if(func(mid > Y))
r = mid;
else
break;
}
if(Y < func(0) || Y > func(100))
printf("No solution!\n");
else
printf("%.4f\n", mid);
}
return 0;
}