解决了qwq...
要多开一列QAQ...
在判断的时候判断xx>1001||yy>1001就好了QAQ..(有大佬给解释下吗)
AC代码：
```cpp
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <queue>
const int N = 1020;
int dx[] = { 0 , 0 , 1 , -1 };
int dy[] = { 1 , -1 , 0 , 0 };
int n , sx , sy;
int mp[N][N] , dis[N][N];
bool inque[N][N];
struct Node {
int x;
int y;
Node ( int x , int y ) : x ( x ) , y ( y ) {}
Node() {}
};
std :: queue < Node > qu;
inline int read () {
int s = 0 , w = 1;
char ch = getchar ();
while ( ch > '9' || ch < '0' ) { if ( ch == '-' ) w = -1; ch = getchar ();}
while ( ch >= '0' && ch <= '9' ) { s = s * 10 + ch - '0'; ch = getchar ();}
return s * w;
}
void Spfa ( int x , int y ) {
memset ( dis , 0x3f3f3f3f , sizeof ( dis ) );
inque[x][y] = 1;
dis[x][y] = 0;
qu.push ( Node ( x , y ) );
while ( !qu.empty () ) {
Node j = qu.front ();
inque[j.x][j.y] = 0;
qu.pop ();
for ( int i = 0 ; i < 4 ; i++ ) {
int xx = j.x + dx[i];
int yy = j.y + dy[i];
if ( xx > 1001 || yy > 1001 || xx < 0 || yy < 0 )
continue;
if ( dis[xx][yy] > dis[j.x][j.y] + mp[xx][yy] ) {
dis[xx][yy] = dis[j.x][j.y] + mp[xx][yy];
if ( !inque[xx][yy] ) {
inque[xx][yy] = 1;
qu.push ( Node ( xx , yy ) );
}
}
}
}
return;
}
int main ( void ) {
//freopen ( "1.txt" , "r" , stdin );
n = read () , sx = read () , sy = read ();
for ( int i = 1 ; i <= n ; i++ ) {
int x = read () , y = read ();
mp[x][y] = 1;
}
Spfa ( sx , sy );
printf ( "%d\n" , dis[0][0] );
return 0;
}
```
by 兮水XiShui丶 @ 2018-09-26 20:26:08
@[Kirito_Rivaille](/space/show?uid=54047)
解释：虽然干草只能在1~1000范围内存在，但是拖拉机可以开到1001去
by 肖恩Sean @ 2019-03-19 19:13:07