poj 2029 树状数组

#include<cstdio>#include<cstring>#define MAX_N 120#define MAX(x,y) ((x)>(y)?(x):(y))int bit[MAX_N][MAX_N];int n,m;void add(int i,int j){for(int k=i;k<=n;k+=k&-k)for(int p=j;p<=m;p+=p&-p)bit[k][p]+=1;}int sum(int i,int j){int res=0;for(int k=i;k>0;k-=k&-k)for(int p=j;p>0;p-=p&-p)res+=bit[k][p];return res;}int main(){int q,res,i,j;while(~scanf("%d",&q)&&q){res=0;int a,b,s,t;memset(bit,0,sizeof(bit));scanf("%d%d",&n,&m);for( i=0;i<q;i++){scanf("%d%d",&a,&b);add(a,b);}scanf("%d%d",&s,&t);for( i=1;i<=n-s+1;i++)for( j=1;j<=m-t+1;j++){res=MAX(res,sum(i+s-1,j+t-1)-sum(i+s-1,j-1)-sum(i-1,j+t-1)+sum(i-1,j-1));}printf("%d\n",res);}}