杭电OJ数组越界Runtime Error (ACCESS_VIOLATION)

Question

#include<algorithm>
#define NN 1005
#define INF 0x3f3f3f3f
using namespace std;
int n,k,m,i,j,a,b,c,d[NN][NN],w[NN][NN],u,flag,sum;
struct edge
{
    int u;
    int v;
    int id;
} ed[NN];

int main()
{

    while(scanf("%d%d",&n,&m)!=EOF)
    {

        for(i=1; i<=m; i++)
        {
            scanf("%d%d",&a,&b);
            ed[i].u=a;
            ed[i].v=b;
            ed[i].id=i;

        }//输入完毕

        for(i=1; i<=m; i++)
        {
             flag=0;
             sum=0;
            for(k=1; k<=n; k++)
            {
                for(j=1; j<=n; j++)
                {
                    w[k][j]=INF;
                    d[k][j]=INF;
                }
            }
            for(j=1; j<=m; j++)
            {
                if(j!=i)
                {
                    a=ed[j].u;
                    b=ed[j].v;
                    w[a][b]=w[b][a]=1;//第x条路被封

                }
            }
            d[1][1]=0;
            for(u=1; u<=n; u++)
                for(k=1; k<=n; k++)
                    for(j=1; j<=n; j++)
                    {


                        d[k][j]=min(d[k][j],d[k][u]+w[u][j]);

                        if(k==j)
                            d[k][j]=0;


                    }
            for(k=1; k<=n; k++)
                for(j=1; j<=n; j++)
                    if((d[k][j]!=INF)&&(!flag))
                    {
                        sum+=d[k][j];

                    }
                    else
                    {

                        flag=1;
                    }
            if(!flag)
                printf("%d\n",sum);
                else
                    printf("INF\n");
        }
    }
}

hdu 2433
http://acm.hdu.edu.cn/showproblem.php?pid=2433
用测试结果没问题，但提交就是
Runtime Error (ACCESS_VIOLATION)
qiu'jie'da