二维数组解决矩阵相加...

#include <stdio.h>
#include <string.h>
int n;
int a[510][510];
int lowbit(int x)
{
    return x&(-x);
}
void inc(int x,int y,int z)
{
    for (int j=x;j<=n;j+=lowbit(j))
    for (int i=y;i<=n;i+=lowbit(i))
        a[j][i]+=z;
}
long long sum(int x,int y)
{
    long long s=0;
    for (int i=x;i>=1;i-=lowbit(i))
        for (int j=y;j>=1;j-=lowbit(j))
             s+=a[i][j];
    return s;
}
int main()
{
    int m,k;
    while (~scanf("%d%d",&n,&m))
    {
        memset(a,0,sizeof(a));
        int i,j;
        for (i=1;i<=n;i++)
            for (j=1;j<=n;j++)
            {
                scanf("%d",&k);
                inc(i,j,k);
            }
        while (m--)
        {
            int x1,y1,x2,y2;
            long long s;
            scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
            s=sum(x2,y2)-sum(x1-1,y2)-sum(x2,y1-1)+sum(x1-1,y1-1);
            printf("%lld\n",s);
        }    
    }
    return 0;

题目链接：http://acm.hrbust.edu.cn/index.php?m=ProblemSet&a=showProblem&problem_id=1693