HUNNU10934 内部收益率
原题链接:http://acm.hunnu.edu.cn/online/?action=problem&type=show&id=10934&courseid=0
double,二分。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include <stdio.h> 2 #include <string.h> 3 #include <math.h> 4 #include <stdlib.h> 5 #define INF 1000000000.0 6 const double eps = 1e-8; 7 double a[11]; 8 int n; 9 10 double cal(double k) 11 { 12 double ans = 0.0; 13 for(int i = 1; i <= n; i ++) 14 { 15 ans += a[i] * pow(k, i + 0.0); 16 } 17 return ans; 18 } 19 20 double bs() 21 { 22 double l = 0.0, r = INF; 23 a[0] = a[0] * (-1); 24 while(r - l > eps) 25 { 26 double mid = (r + l) * 0.5; 27 double tmp = cal(mid); 28 if(tmp >= a[0]) 29 r = mid; 30 else 31 l = mid; 32 } 33 return l; 34 } 35 36 int main() 37 { 38 int i; 39 while(scanf("%d", &n), n > eps) 40 { 41 scanf("%lf", &a[0]); 42 for(i = 1; i <= n; i ++) 43 scanf("%lf", &a[i]); 44 45 double ans = bs(); 46 if(ans > INF - 1.0) 47 { 48 printf("No\n"); 49 continue; 50 } 51 ans = 1.0 / ans; 52 ans -= 1.0; 53 printf("%.2f\n", ans); 54 } 55 return 0; 56 }