你没有判断是否在队列中；
即inq[][]；
cpp
```cpp
#include<algorithm>
#include<iostream>
#include<queue>
using namespace std;
queue <short> x,y;
int n,m,a[405][405];
int inq[1234][1324]; //******************************
int ans1,ans2;
int main(){
ios::sync_with_stdio(false);
int m1,m2,bx,by;
cin>>n>>m>>m1>>m2;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
cin>>a[i][j];
if(a[i][j]==4)
ans1=i,ans2=j;
if(a[i][j]==3)
bx=i,by=j;
}
}
x.push(bx);
y.push(by);
a[bx][by]=0;
inq[bx][by]=1; //************************************
const int zh[8][2]={
{m1,m2},
{m1,-m2},
{-m1,m2},
{-m1,-m2},
{m2,m1},
{m2,-m1},
{-m2,m1},
{-m2,-m1}
};
int i,j,u,xx,yy;
while(!(x.empty())){
xx=x.front();
yy=y.front();
x.pop();
y.pop();
for(u=0;u<8;u++){
i=xx+zh[u][0];
j=yy+zh[u][1];
if(i>=1 && i<=n && j>=1 && j<=m && (a[i][j]==1||a[i][j]==4)&&!inq[i][j]){
x.push(i);
y.push(j);
a[i][j]=a[xx][yy]+1;
inq[i][j]=1; //**************************
}
}
}
cout<<a[ans1][ans2];
return 0;
}
```
by wuzhoupei @ 2017-09-20 11:19:20