C :

#include"stdio.h"
#define min(x,y) x<y?x:y;
int map[9][9] = {1,1,1,1,1,1,1,1,1,
                 1,0,0,1,0,0,1,0,1,
                 1,0,0,1,1,0,0,0,1,
                 1,0,1,0,1,1,0,1,1,
                 1,0,0,0,0,1,0,0,1,
                 1,1,0,1,0,1,0,0,1,
                 1,1,0,1,0,1,0,0,1,
                 1,1,0,1,0,0,0,0,1,
                 1,1,1,1,1,1,1,1,1};
int x2,y2,m;
int dfs(int x,int y,int s)
{
    if(map[x][y])return;
    if(x == x2&&y == y2)
    {
        m = min(s,m);
        return;
    }
    s++;
    map[x][y] = 1;
    dfs(x+1,y,s);
    dfs(x,y+1,s);
    dfs(x-1,y,s);
    dfs(x,y-1,s);
    map[x][y] = 0;
}

int main()
{
    int x1,y1,n;
    scanf("%d",&n);
    while(n--)
    {
        m = 100;
        scanf("%d %d %d %d",&x1,&y1,&x2,&y2);
        dfs(x1,y1,0);
        printf("%d\n",m);
    }
    return 0;
}

C++ :

#include<cstdio>
#define min(x,y) x>y?y:x
int maze[9][9]={1,1,1,1,1,1,1,1,1,
                1,0,0,1,0,0,1,0,1,
                1,0,0,1,1,0,0,0,1,
                1,0,1,0,1,1,0,1,1,
                1,0,0,0,0,1,0,0,1,
                1,1,0,1,0,1,0,0,1,
                1,1,0,1,0,1,0,0,1,
                1,1,0,1,0,0,0,0,1,
                1,1,1,1,1,1,1,1,1};
int a,b,c,d,m;
void dfs(int x,int y,int s){
  if(maze[x][y]) return;
  if(x == c && y == d){
    m = min(s,m);
    return;
  }
  s++;
  maze[x][y]=1;
  dfs(x+1,y,s);
  dfs(x,y+1,s);
  dfs(x-1,y,s);
  dfs(x,y-1,s);
  maze[x][y]=0;
}

int main(){
  int n;
  scanf("%d",&n);
  while(n--){
    m=9999;
    scanf("%d%d%d%d",&a,&b,&c,&d);
    dfs(a,b,0);
    printf("%d\n",m);
  }
  return 0;
}