POJ 3026 Brog Maze

解题思路：BFS 找出所有点之间的最短距离，Prim求解最小生成树

#include <iostream>
using namespace std;

#define MaxNum 30000

struct point
{
    int x,y;
};

int main()
{
    int n, row, col, vn, begin, end, x, y, start, tempS, min, t;
    string str;
    char map[55][55];
    short dist[55][55];
    point as[105], queue[3000];
    const int direc[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
    int minDist[105][105];

    int PrimDist[105];
    bool visited[105];

    cin >> n;
    while (n--)
    {
        vn = 0;
        cin >> col >> row;
        while(getchar() != '\n');
        for (int i = 0; i < row; i++)
        {
            cin.getline(map[i], 55);
            for (int j = 0; j < col; j++)
            {
                if (map[i][j] == 'A' || map[i][j] == 'S')
                {
                    as[vn].x = j;
                    as[vn].y = i;
                    vn++;
                }
            }
        }
        for (int i = 0; i < vn - 1; i++)
        {
            fill(&dist[0][0], &dist[54][55], MaxNum);
            dist[as[i].y][as[i].x] = 0;
            queue[0] = as[i];
            begin = end = 0;
            while (begin <= end)
            {
                for (int j = 0; j < 4; j++)
                {
                    x = queue[begin].x + direc[j][0];
                    y = queue[begin].y + direc[j][1];
                    if (dist[y][x] > (dist[queue[begin].y][queue[begin].x] + 1) && map[y][x] != '#')
                    {
                        dist[y][x] = dist[queue[begin].y][queue[begin].x] + 1;
                        end++;
                        queue[end].x = x;
                        queue[end].y = y;
                    }
                }
                begin++;
            }
            for (int j = 0; j < vn; j++)
                minDist[i][j] = minDist[j][i] = dist[as[j].y][as[j].x];
        }
        minDist[vn - 1][vn - 1] = 0;

        fill(&PrimDist[1], &PrimDist[vn], MaxNum);
        memset(visited, 0, sizeof(bool) * vn);
        PrimDist[0] = 0;
        start = 0;
        while (start != -1)
        {
            visited[start] = true;
            tempS = -1;
            min = MaxNum;

            for (int i = 0; i < vn; i++)
            {
                if (!visited[i])
                {
                    if (PrimDist[i] > minDist[start][i])
                        PrimDist[i] = minDist[start][i];
                    if (min > PrimDist[i])
                    {
                        min = PrimDist[i];
                        tempS = i;
                    }
                }
            }
            start = tempS;
        }
        t = 0;
        for (int i = 0; i < vn; i++)
            t += PrimDist[i];
        printf("%d\n", t);
    }
    return 0;
}