uva 12086 - Potentiometers

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <stdlib.h>
 4 #include <iostream>
 5 int b[300000],a[300000],n;
 6 int lowbit(int x)
 7 {
 8     return x&(-x);
 9 }
10 int sum(int x)
11 {
12     int sum=0;
13     while(x>0)
14     {
15         sum=sum+b[x];
16         x=x-lowbit(x);
17     }
18     return sum;
19 }
20 void add(int i,int x)
21 {
22     while(i<=n)
23     {
24         b[i]=b[i]+x;
25         i=i+lowbit(i);
26     }
27 }
28 int main()
29 {
30     int t=1;
31     int cx=0;
32     while(scanf("%d",&n)!=EOF&&n)
33     {
34         if(cx)
35             puts("");
36         memset(b,0,sizeof(b));
37         int  d,e,x;
38         char c[10];
39         for(int i=1; i<=n; i++)
40         {
41             scanf("%d",&a[i]);
42             add(i,a[i]);
43         }
44         printf("Case %d:\n",t++);
45         while(1)
46         {
47             scanf("%s",c);
48             if(strcmp(c,"END")==0)
49                 break;
50             if(c[0]==‘M‘)
51             {
52                 scanf("%d%d",&d,&e);
53                 printf("%d\n",sum(e)-sum(d-1));
54             }
55             if(c[0]==‘S‘)
56             {
57                 scanf("%d%d",&d,&e);
58                 x=e-a[d];
59                 a[d]=e;
60                 add(d,x);
61             }
62         }
63         cx=n;
64     }
65     return 0;
66 }