hdu Can you solve this equation?
Can you solve this equation? |
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) |
Total Submission(s): 412 Accepted Submission(s): 237 |
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.
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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);
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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.
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Sample Input
2 100 -4 |
Sample Output
1.6152 No solution! |
Author
Redow
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Recommend
lcy
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分析:典型二分,注意eps取值要恰当
#include<cmath> #include<cstdio> #define eps 1e-8 double fun(double x) { return 8*x*x*x*x + 7*x*x*x + 2*x*x + 3*x + 6; } int main() { double y,a,b,m,d; int T; scanf("%d",&T); while(T--) { scanf("%lf",&y); if(y<6 || y>807020306) { printf("No solution!\n"); continue; } a=0.0; b=100.0; while(b-a>eps) { m=(a+b)/2; if(fun(m)<y) a=m; else b=m; } printf("%.4f\n",a); } return 0; }
这条路我们走的太匆忙~拥抱着并不真实的欲望~