POJ 2481 Cows【树状数组】

题意:给出n头牛的s,e 如果有两头牛,现在si <= sj && ei >= ej

那么称牛i比牛j强壮 然后问每头牛都有几头牛比它强壮

先按照s从小到大排序,然后用e来当做树状数组里面那个a数组,对于每头牛求出前面比他大的e有多少个

还有就是注意有两头牛的s和e相等的情况,就只需要更新值,

 1 #include<iostream>  
 2 #include<cstdio>  
 3 #include<cstring> 
 4 #include <cmath> 
 5 #include<stack>
 6 #include<vector>
 7 #include<map> 
 8 #include<set>
 9 #include<queue> 
10 #include<algorithm>  
11 using namespace std;
12 
13 typedef long long LL;
14 const int INF = (1<<30)-1;
15 const int mod=1000000007;
16 const int maxn=100005;
17 
18 int a[maxn];
19 int c[maxn];//树状数组
20 int ans[maxn];//
21 
22 struct node{
23     int s,e;
24     int id;
25 } p[maxn];
26 
27 int cmp(node n1,node n2){
28     if(n1.s != n2.s) return n1.s < n2.s;
29     return n1.e > n2.e;
30 }
31 
32 int n;
33 
34 int lowbit(int x){ return x & (-x);} 
35 
36 int sum(int x){
37     int ret=0;
38     while( x>0){
39         ret+=c[x];x-=lowbit(x);
40     }
41     return ret;
42 }
43 
44 void add(int x,int d){
45     while(x < maxn){
46         c[x]+=d; x+=lowbit(x);
47     }
48 }
49 
50 int main(){
51     while(scanf("%d",&n)!=EOF){
52         if(n == 0) break;
53         for(int i=1;i<=n;i++) scanf("%d %d",&p[i].s,&p[i].e),p[i].id=i;
54         sort(p+1,p+n+1,cmp);
55         
56         memset(c,0,sizeof(c));
57         memset(ans,0,sizeof(ans));
58         
59         for(int i=1;i<=n;i++){
60             
61             if(i!=1 && p[i].s == p[i-1].s && p[i].e == p[i-1].e) ans[p[i].id] = ans[p[i-1].id];
62             else {
63                 ans[p[i].id] = (i-1 ) - sum(p[i].e-1);
64             }
65             add(p[i].e,1);
66         }
67         
68         printf("%d",ans[1]); 
69         for(int i=2;i<=n;i++) printf(" %d",ans[i]);
70         printf("
");
71     }
72     return 0;
73 }  
View Code
原文地址:https://www.cnblogs.com/wuyuewoniu/p/4592308.html