hdu 2642 Stars

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思路: 二维树状数组

分析: 裸题

代码:

 /************************************************
* By: chenguolin *
* Date: 2013-08-21 *
* Address: http://blog.csdn.net/chenguolinblog *
***********************************************/
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;

const int MAXN = 1010;

int m;
int num[MAXN][MAXN];
int treeNum[MAXN][MAXN];

int lowbit(int x){
return x&(-x);
}

int getSum(int x , int y){
int sum = 0;
for(int i = x ; i > 0 ; i -= lowbit(i))
for(int j = y ; j > 0 ; j -= lowbit(j))
sum += treeNum[i][j];
return sum;
}

void add(int x , int y , int val){
for(int i = x ; i < MAXN ; i += lowbit(i))
for(int j = y ; j < MAXN ; j += lowbit(j))
treeNum[i][j] += val;
}

void solve(){
memset(num , 0 , sizeof(num));
memset(treeNum , 0 , sizeof(treeNum));
char c;
int x , y , val;
int x1 , x2 , y1 , y2;
int x3 , x4 , y3 , y4;
while(m--){
scanf("%c" , &c);
if(c == 'B'){
scanf("%d%d%*c" , &x , &y);
x++ , y++;
val = num[x][y] ? 0 : 1;
if(val)
add(x , y , val);
num[x][y] = 1;
}
else if(c == 'D'){
scanf("%d%d%*c" , &x , &y);
x++ , y++;
if(num[x][y])
add(x , y , -1);
num[x][y] = 0;
}
else{
scanf("%d%d" , &x1 , &x2);
scanf("%d%d%*c" , &y1 , &y2);
x1++ , x2++ , y1++ , y2++;
x3 = min(x1 , x2) , y3 = min(y1 , y2);
x4 = max(x1 , x2) , y4 = max(y1 , y2);
int ans = getSum(x4 , y4);
ans -= getSum(x3-1 , y4);
ans -= getSum(x4 , y3-1);
ans += getSum(x3-1 , y3-1);
printf("%d\n" , ans);
}
}
}

int main(){
while(scanf("%d%*c" , &m) != EOF)
solve();
return 0;
}