HDU 2199 Can you solve this equation? (二分 水题)
Can you solve this equation?
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 6023 Accepted Submission(s): 2846
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.
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!
Author
Redow
一道初学者的二分题,讲课用
#include <iostream> #include <cstdio> using namespace std; double y; double getfx(double x){ return 8*x*x*x*x + 7*x*x*x + 2*x*x + 3*x + 6; } void computing(){ if(getfx(100)<y-1e-3 || getfx(0)>y+1e-3){ printf("No solution!\n"); return; } double l=0,r=100; while(r-l>1e-6){ double mid=(l+r)/2; if(getfx(mid)>y) r=mid; else l=mid; } printf("%.4lf\n",r); } int main(){ int t; scanf("%d",&t); while(t-- >0){ scanf("%lf",&y); computing(); } return 0; }