POJ 2481Cows（树状数组 + 好题）

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <map>
 5 #include <algorithm>
 6 #include <string.h>
 7 using namespace std;
 8 const int MAX = 100000 + 10;
 9 struct node
10 {
11     int s,e;
12     int index;
13 };
14 node a[MAX];
15 int c[MAX],cnt[MAX];
16 int cmp(node x,node y)
17 {
18     if(x.e == y.e)
19         return x.s < y.s;
20     return x.e > y.e;
21 }
22 int lowbit(int k)
23 {
24     return k & (-k);
25 }
26 void add (int k,int num)
27 {
28     for(int i = k; i < MAX; i += lowbit(i))
29         c[i] += num;
30 }
31 int sum(int k)
32 {
33     int s = 0;
34     for(int i = k; i > 0; i -= lowbit(i))
35         s += c[i];
36     return s;
37 }
38 int main()
39 {
40     int n;
41     while(scanf("%d", &n) != EOF && n)
42     {
43         for(int i = 0; i < n; i++)
44         {
45             scanf("%d%d", &a[i].s, &a[i].e);
46             a[i].index = i;
47         }
48         sort(a,a + n,cmp);
49         memset(c,0,sizeof(c));
50         memset(cnt,0,sizeof(cnt));
51         cnt[a[0].index] = 0;
52         add (a[0].s + 1, 1);
53         for(int i = 1; i < n; i++)
54         {
55             if(a[i].s == a[i - 1].s && a[i].e == a[i - 1].e)
56                 cnt[a[i].index] = cnt[a[i - 1].index];
57             else
58                 cnt[a[i].index] = sum(a[i].s + 1);
59             add(a[i].s + 1,1);
60         }
61         printf("%d",cnt[0]);
62         for(int i = 1; i < n; i++)
63             printf(" %d",cnt[i]);
64         printf("\n");
65     }
66 
67     return 0;
68 }