POJ 1195 Mobile phones

题目链接：http://poj.org/problem?id=1195

二维树状数组的应用

#include <cstdio>
#include <cstring>
#include <cstdlib>

const int MAXN = 1200;
int S;
int C[MAXN][MAXN];

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

void Add( int x, int y, int add )
{
    int tpy;
    while ( x <= S )
    {
        tpy = y;
        while ( tpy <= S )
        {
            C[x][tpy] += add;
            tpy += lowbit(tpy);
        }
        x += lowbit(x);
    }
    return;
}

int Sum( int x, int y )
{
    int ret = 0;
    while ( x > 0 )
    {
        int tpy = y;
        while ( tpy > 0 )
        {
            ret += C[x][tpy];
            tpy -= lowbit(tpy);
        }
        x -= lowbit(x);
    }
    return ret;
}

int main()
{
    int op, add;
    int x1, y1, x2, y2;
    while( ~scanf( "%d%d", &op, &S ) )
    {
        memset( C, 0, sizeof(C) );
        while ( scanf( "%d", &op ), op != 3 )
        {
            if ( op == 1 )
            {
                scanf( "%d%d%d", &x1, &y1, &add );
                ++x1, ++y1;
                Add( x1, y1, add );
            }
            else
            {
                scanf( "%d%d%d%d", &x1, &y1, &x2, &y2 );
                ++x1, ++y1;
                ++x2, ++y2;
                printf("%d\n", Sum(x2, y2) - Sum(x1 - 1, y2) - Sum(x2, y1 - 1) + Sum(x1 - 1, y1 - 1) );
            }
        }
    }
    return 0;
}