HDU 4803 贪心

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 using namespace std;
 5 
 6 int main()
 7 {
 8   //  freopen("a.in" , "r" , stdin);
 9     int x , y;
10     while(scanf("%d%d" , &x , &y) == 2)
11     {
12         if(y<x){
13             puts("-1");
14             continue;
15         }
16         double ave = (y+0.999999)/x;
17         double cur = 1.0;
18         int cnt = x-1 , ax = 1;
19         while(1)
20         {
21             if(ax == x+1) break;
22             int t = (int)(ave*ax - cur);
23             cur += t , cnt += t;
24             cur += cur/ax;
25             ax++;
26         }
27         printf("%d\n" , cnt);
28     }
29     return 0;
30 }