poj3026

最小生成树，要注意多余的空格（包括x,y那行）

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

#define maxn 105
#define inf 0x3f3f3f3f

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

int n, m;
bool map[maxn][maxn];
int dist[maxn][maxn];
char st[maxn][maxn];
int tot;
int dir[4][2] =
{
{ 0, 1 },
{ 1, 0 },
{ -1, 0 },
{ 0, -1 } };
int vis[maxn];
int lowc[maxn];
int cost[maxn][maxn];

void input()
{
    scanf("%d%d", &m, &n);
    gets(st[0]);
    for (int i = 0; i < n; i++)
        gets(st[i]);
    tot = 1;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
        {
            if (st[i][j] == '#')
                map[i][j] = false;
            else
                map[i][j] = true;
            if (st[i][j] == 'S')
            {
                point[0].x = i;
                point[0].y = j;
            }
            if (st[i][j] == 'A')
            {
                point[tot].x = i;
                point[tot].y = j;
                tot++;
            }
        }
}

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

void bfs(Point &a)
{
    memset(dist, -1, sizeof(dist));
    int front, rear;
    front = rear = 0;
    q[rear++] = a;
    dist[a.x][a.y] = 0;
    Point temp;
    while (front != rear)
    {
        temp = q[front++];
        if (front == maxn * maxn)
            front = 0;
        Point b;
        for (int i = 0; i < 4; i++)
        {
            b.x = temp.x + dir[i][0];
            b.y = temp.y + dir[i][1];
            if (ok(b))
            {
                q[rear++] = b;
                if (rear == maxn * maxn)
                    rear = 0;
                dist[b.x][b.y] = dist[temp.x][temp.y] + 1;
            }
        }
    }
}

void make()
{
    for (int i = 0; i < tot; i++)
    {
        bfs(point[i]);
        for (int j = 0; j < tot; j++)
            cost[i][j] = dist[point[j].x][point[j].y];
    }
}

int prim(int n)
{
    int i, j, p;
    int minc, res = 0;
    memset(vis, 0, sizeof(vis));
    vis[0] = 1;
    for (i = 1; i < n; i++)
        lowc[i] = cost[0][i];
    for (i = 1; i < n; i++)
    {
        minc = inf;
        p = -1;
        for (j = 0; j < n; j++)
            if (0 == vis[j] && minc > lowc[j])
            {
                minc = lowc[j];
                p = j;
            }
        if (inf == minc)
            return -1;
        res += minc;
        vis[p] = 1;
        for (j = 0; j < n; j++)
            if (0 == vis[j] && lowc[j] > cost[p][j])
                lowc[j] = cost[p][j];
    }
    return res;
}

int main()
{
    //freopen("t.txt", "r", stdin);
    int t;
    scanf("%d", &t);
    while (t--)
    {
        input();
        make();
        printf("%d\n", prim(tot));
    }
    return 0;
}