URAL 1033 Labyrinth

URAL_1033

    要注意下两个entrance不一定是连通的，然后用dfs计数就可以了。

#include<stdio.h>

#include<string.h>

#define MAXD 40

int N, g[MAXD][MAXD], vis[MAXD][MAXD];

char b[MAXD];

int dx[] = {-1, 1, 0, 0}, dy[] = {0, 0, -1, 1};

void init()

{

    int i, j, k;

    memset(g, 0, sizeof(g));

    for(i = 1; i <= N; i ++)

    {

        scanf("%s", b + 1);

        for(j = 1; j <= N; j ++)

            if(b[j] == '.')

                g[i][j] = 1;

    }

}

void dfs(int x, int y, int &ans)

{

    int i, newx, newy;

    vis[x][y] = 1;

    for(i = 0; i < 4; i ++)

    {

        newx = x + dx[i], newy = y + dy[i];

        if(!g[newx][newy])

                ++ ans;

        else if(!vis[newx][newy])

            dfs(newx, newy, ans);

    }

}

void solve()

{

    int i, j, k, ans = 0;

    memset(vis, 0, sizeof(vis));

    dfs(1, 1, ans);

    if(!vis[N][N])

        dfs(N, N, ans);

    printf("%d\n", (ans - 4) * 9);

}

int main()

{

    while(scanf("%d", &N) == 1)

    {

        init();

        solve();

    }

    return 0;

}