二分法查找基础
2016-05-04 19:57
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杭电2199Can you solve this equation?
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!
这题是二分法查找。直接套模板
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!
这题是二分法查找。直接套模板
#include<stdio.h> #include<math.h> double f(double x) { return 8*pow(x,4.0)+7*pow(x,3.0)+2*pow(x,2.0)+3*x+6; } int main() { int n; double m, l, ll, ans, mm; scanf("%d",&n); while(n--){ scanf("%lf",&m); l = 0; ll = 100; if(m >= f(0) && m <= f(100)){//外界条件 ; while(ll-l > 1e-9){//精确度 ; mm = (ll + l)/2; double ans = f(mm); if(ans > m){//二分法; ll = mm-1e-9; } else{ l = mm+1e-9; } } printf("%.4lf\n",(ll+l)/2); } else printf("No solution!\n"); } return 0 ; }
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