Knight Moves BFS 水题

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <queue>
#include <algorithm>

using namespace std;

int xx[ ] = {1,2,-1,-2,-2,-1,1,2};
int yy[ ] = {2,1,-2,-1,1,2,-2,-1};

int map[10][10];
int a, b, c, d, f1 = 0;

int judge( int x, int y)
{
    if ( x < 1 || x > 8 || y < 1 || y > 8)
    return  0;
    return 1;
}

struct node
{
    int x, y, t;
}NODE;

void BFS(  )
{
    int i, j, x1, x2, y1, y2, t;
    queue<node>q;
    NODE.x = a, NODE.y = b, NODE.t = 0;
    q.push(NODE);
    while ( !q.empty( ))
    {
        NODE = q.front( );
        q.pop( );
        x1 = NODE.x, y1 = NODE.y, t = NODE.t;
        if (x1 == c && y1 == d)
            {
                f1 = t;
                break;
            }
        for (i = 0; i < 8; i++)
        {
            x2 = x1 + xx[i];
            y2 = y1 + yy[i];
            if (judge(x2,y2))
            {
                NODE.x = x2, NODE.y = y2, NODE.t = t + 1;
                q.push(NODE);
            }
        }
    }
}


int main( )
{
    char ch1[10], ch2[10];
    
    while (scanf("%s%s",ch1, ch2) != EOF)
    {   
        f1 = 0;
        a = ch1[0] - 'a' + 1;
        b = ch1[1] - '0';
        c = ch2[0] - 'a' + 1;
        d = ch2[1] - '0';
        BFS( );
        printf("To get from %s to %s takes %d knight moves.\n",ch1, ch2, f1);
    }
    return 0;
}