UVa439

Knight Moves

题意:骑士巡游到某位置的最少步数

#include <stdio.h>
#include <string.h>

int s[20][20];
int rear, front;
int min;
char a, c;
int b, d;

struct
{
    int x, y;
    int p;
}Susake[300000];

void bfs(int n, int m)
{
    int t;
    rear++;
    Susake[rear].x = n;
    Susake[rear].y = m;
    Susake[rear].p = 0;
    if(n == c - 96 && m == d)
    {
        min = Susake[rear].p;
        return ;
    }
    while(front != rear)
    {
        front++;
        t = front;
        if(s[Susake[t].x - 2][Susake[t].y + 1])
        {
            rear++;
            Susake[rear].x = Susake[t].x - 2;
            Susake[rear].y = Susake[t].y + 1;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }
        }
        if(s[Susake[t].x + 2][Susake[t].y + 1])
        {
            rear++;
            Susake[rear].x = Susake[t].x + 2;
            Susake[rear].y = Susake[t].y + 1;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }
        }
        if(s[Susake[t].x - 1][Susake[t].y + 2])
        {
            rear++;
            Susake[rear].x = Susake[t].x - 1;
            Susake[rear].y = Susake[t].y + 2;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }
        }
        if(s[Susake[t].x - 2][Susake[t].y - 1])
        {
            rear++;
            Susake[rear].x = Susake[t].x - 2;
            Susake[rear].y = Susake[t].y - 1;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }
        }
        if(s[Susake[t].x - 1][Susake[t].y - 2])
        {
            rear++;
            Susake[rear].x = Susake[t].x - 1;
            Susake[rear].y = Susake[t].y - 2;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }
        }
        if(s[Susake[t].x + 1][Susake[t].y - 2])
        {
            rear++;
            Susake[rear].x = Susake[t].x + 1;
            Susake[rear].y = Susake[t].y - 2;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }
        }
        if(s[Susake[t].x + 2][Susake[t].y - 1])
        {
            rear++;
            Susake[rear].x = Susake[t].x + 2;
            Susake[rear].y = Susake[t].y - 1;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }        }
        if(s[Susake[t].x + 1][Susake[t].y + 2])
        {
            rear++;
            Susake[rear].x = Susake[t].x + 1;
            Susake[rear].y = Susake[t].y + 2;
            Susake[rear].p = Susake[t].p + 1;
            if(Susake[rear].x == c - 96 && Susake[rear].y == d)
            {
                min = Susake[rear].p;
                return ;
            }
        }
    }
}

int main(int argc, char *argv[])
{
    int i, j;
    while(scanf("%c%d%*c%c%d%*c", &a, &b, &c, &d) != EOF)
    {
        memset(s, 0, sizeof(s));
        front = rear = 0;
        for(i = 1; i <= 8; i++)
            for(j = 1; j <= 8; j++)
                s[i][j] = 1;
        bfs(a - 96, b);
        printf("To get from %c%d to %c%d takes %d knight moves.\n", a, b, c, d, min);
    }
    return 0;
}

UVa439,布布扣,bubuko.com