poj3984

简单题

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define maxn 10

struct Point
{
    int x, y;
}q[maxn * maxn], stk[maxn * maxn];

int map[maxn][maxn];
int cost[maxn][maxn];
int from[maxn][maxn];
int dir[4][2] =
{
{ 1, 0 },
{ 0, 1 },
{ -1, 0 },
{ 0, -1 } };

bool ok(Point &a)
{
    if (a.x < 0 || a.y < 0 || a.x >= 5 || a.y >= 5)
        return false;
    return !map[a.x][a.y] && (cost[a.x][a.y] == -1);
}

int main()
{
    //freopen("t.txt", "r", stdin);
    for (int i = 0; i < 5; i++)
        for (int j = 0; j < 5; j++)
            scanf("%d", &map[i][j]);
    int l = 0;
    int r = 1;
    q[0].x = 0;
    q[0].y = 0;
    memset(cost, -1, sizeof(cost));
    cost[0][0] = 0;
    while (l != r)
    {
        for (int i = 0; i < 4; i++)
        {
            Point p;
            p.x = q[l].x + dir[i][0];
            p.y = q[l].y + dir[i][1];
            if (ok(p))
            {
                q[r++] = p;
                from[p.x][p.y] = i;
                cost[p.x][p.y] = cost[q[l].x][q[l].y] + 1;
            }
        }
        l++;
    }
    int top = 0;
    Point a;
    a.x = 4;
    a.y = 4;
    int t;
    while (!(a.x == 0 && a.y == 0))
    {
        stk[top++] = a;
        t = from[a.x][a.y];
        a.x -= dir[t][0];
        a.y -= dir[t][1];
    }
    printf("(0, 0)\n");
    while (top--)
        printf("(%d, %d)\n", stk[top].x, stk[top].y);
    return 0;
}