visit数组不能用有多余的行 列

#include<stdio.h>
#include<string.h>
const int MAXN = 8;
int visit[MAXN][MAXN];
int dist[MAXN][MAXN];
int q[MAXN*MAXN];
int dx[8]={-2,-2,-1,-1,+1,+1,+2,+2};
int dy[8]={-1,+1,-2,+2,-2,+2,-1,+1};
int bfs(int i,int j,int ii,int jj);
int main()
{
	//
	freopen("input.txt","r",stdin);
	char s1[5];
	char s2[5];
	while(scanf("%s%s",s1,s2)==2)
	{
		int sr = s1[1]-'1';
		int sc = s1[0]-'a';
		int er = s2[1]-'1';
		int ec = s2[0]-'a';
		memset(visit,0,sizeof(visit));
		int dis = bfs(sr,sc,er,ec);
		printf("To get from %s to %s takes %d knight moves.\n",s1,s2,dis);
	}
}
int bfs(int i,int j,int ii,int jj)
{
	int front = 0;
	int rear = 0;
	int u=i*MAXN+j;
	q[rear++] = u;
	visit[i][j] = 1;
	dist[i][j] = 0;
	if(i == ii && j==jj)
	    return dist[i][j];
	while(front<rear)
	{
		u = q[front++];
		i = u/MAXN;
		j = u%MAXN;
		for(int d = 0; d < 8;d++)
		{
			int ni = i + dx[d];
			int nj = j + dy[d];
			if(ni>=0&&ni<MAXN&&nj>=0&&nj<MAXN&&!visit[ni][nj])  //此处ni,nj上限必须为实际行列数
			{
				q[rear++] = ni*MAXN+nj;
				visit[ni][nj] = 1;
				dist[ni][nj] = dist[i][j]+1;
				if(ni == ii && nj==jj)
					return dist[ni][nj];
			}
		}
	}
}