Can you solve this equation? Time Limit : 2000/1000ms (Java/Other) Memory Limit : 32768/32768K (Java/Other) Total Submission(s) : 186 Accepted Submiss ...
Can you solve this equation?
Time Limit : 2000/1000ms (Java/Other) Memory Limit : 32768/32768K (Java/Other)
Total Submission(s) : 186 Accepted Submission(s) : 59
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;<br>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 -4Sample Output 1.6152 No solution!
簡單題意:
給出一個方程,求解方程,註意Y的範圍。
思路:
用二分法求解,
# include <iostream> # include <cmath> using namespace std; double f(double x, double y) { double fx = 8 * pow(x, 4) + 7 * pow(x, 3) + 2 * pow(x, 2) + 3 * x + 6 - y; return fx; } int main() { int t; cin >> t; while(t--) { double y; cin >> y; double begin = 0, end = 100, mid; int i = 0; while(1) { if(y < 6 || y > 8.0702e+8) { cout << "No solution!" << endl; break; } mid = (begin + end) / 2; if(fabs(f(mid, y)) <= 0.0001) { cout.precision(4); cout << fixed << mid << endl; break; } else if(f(mid, y) > 0) { end = mid; } else if(f(mid, y) < 0) { begin = mid; } //cout << mid << endl; } } return 0; }