2015.11.8 ---2013.南京

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<algorithm>
 5 using namespace std;
 6 
 7 int n;
 8 string p[15] = {"A","A-","B+","B","B-",
 9                 "C+","C","C-","D","D-","F"};
10 double a[15] = {4.0,3.7,3.3,3.0,2.7,2.3,2.0,1.7,
11                 1.3,1.0,0.0};
12 
13 int main(){
14     while(scanf("%d",&n) != EOF){
15         int x;
16         char s[105];
17         double fz = 0.0,fm = 0.0;
18         for(int i = 1;i <= n;i++){
19             scanf("%d %s",&x,s);
20             getchar();
21            // printf("s = %s\n",s);
22             if(s[0] == ‘P‘ || s[0] == ‘N‘) continue;
23             for(int j = 0;j < 11;j++){
24                 if(s == p[j]){
25                       //  printf("a[%d] = %d  p[%d] = %s  \n",j,a[j],j,p[j].c_str());
26                         fz += x*a[j];
27                         fm += x;
28                         double l = x*a[j];
29                         double r = x;
30                       //  printf("l = %lf r = %lf \n",l,r);
31                         break;
32                 }
33             }
34         }
35         if(fz == 0 || fm == 0) puts("0.00");
36         else{
37             printf("%.2lf\n",fz/fm);
38         }
39     }
40     return 0;
41 }

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<algorithm>
 5 using namespace std;
 6 
 7 int x,y;
 8 
 9 int main(){
10     while(scanf("%d %d",&x,&y) != EOF){
11         if(y < x) {
12             puts("-1");
13             continue;
14         }
15         double pj = (y+0.99999)/x;
16         int cnt = x-1;
17         double cx = 1.0,cy = 1.0;
18         for(cx = 1;cx <= x;cx++){
19             int time = pj*cx-cy;
20             cnt += time;
21             cy += 1.0*time;
22             cy += cy/cx;
23         }
24         printf("%d\n",cnt);
25     }
26     return 0;
27 }