POj 2029 (二维树状数组)

让人郁闷的是，竟然比暴力还慢。。

#include<iostream>#include<string.h>#include<string>#include<stdio.h>using namespace std;template<class ValueType,int xMaxSize,int yMaxSize>class TreeArrayTwo{ public: TreeArrayTwo():xSize(xMaxSize),ySize(xMaxSize){memset(ta,0,sizeof(ta));} int low(int n){return n&(-n);} void clear() { memset(ta,0,sizeof(ta)); } void add(int x,int y,ValueType v){for(int i=x;i<=xSize;i+=low(i))for(int j=y;j<=ySize;j+=low(j))ta[i][j]+=v;} ValueType sum(int x,int y){ValueType v=0;for(int i=x;i>0;i-=low(i))for(int j=y;j>0;j-=low(j))v+=ta[i][j];return v;} public: ValueType ta[xMaxSize][yMaxSize]; int xSize,ySize;};TreeArrayTwo<int,510,510> tr;void show(){for(int i=1;i<=tr.xSize;i++){for(int j=1;j<=tr.ySize;j++)cout<<tr.ta[i][j]<<" ";cout<<endl;}}int main(){ freopen("1.txt","r",stdin); int n; int x,y,w,h; while(cin>>n&&n){ tr.clear(); cin>>tr.xSize>>tr.ySize; for(int i=0;i<n;i++){ cin>>x>>y; tr.add(x,y,1); } //show(); int max1=0; cin>>w>>h; for(int i=w;i<=tr.xSize;i++) for(int j=h;j<=tr.ySize;j++) max1=max(max1,tr.sum(i,j)+tr.sum(i-w,j-h)-tr.sum(i-w,j)-tr.sum(i,j-h)); cout<<max1<<endl; } }