UVA - 10307 Killing Aliens in Borg Maze（最小生成树kruskal+bfs）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;

const int mnx = 110;
const int mxe = 50100;

int dirx[4] = { 1, -1, 0, 0 };
int diry[4] = { 0, 0, 1, -1 };

char map[mnx][mnx];
bool vis[mnx][mnx];
int dis[mnx][mnx];

struct point
{
	int x, y;
}p[mnx*mnx];

struct edge
{
	int u, v, c;
	bool operator < (edge & b) const
	{
		return c < b.c;
	}
}e[mxe];

int fa[mnx];
int n, m;
int c, r;

int find(int t)
{
	if (fa[t] != t) fa[t] = find(fa[t]);
	return fa[t];
}

int kruskal()
{
	sort(e + 1, e + 1 + m);
	for (int i = 1; i <= n; i++)
		fa[i] = i;
	int ret = 0;
	for (int i = 1; i <= m; i++)
	{
		int u = e[i].u, v = e[i].v, c = e[i].c;
		u = find(u), v = find(v);
		if (u != v)
		{
			ret += c;
			fa[u] = v;
		}
	}
	return ret;
}

int BFS(point s,point en)
{
	int ret = 0;
	memset(vis, false, sizeof(vis));
	memset(dis, 0, sizeof(dis));
	queue<point>que;
	que.push(s);
	vis[s.x][s.y] = true;
	dis[s.x][s.y] = 0;
	while (!que.empty())
	{
		point p = que.front();
		que.pop();
		int x = p.x, y = p.y;

		if (x == en.x && y == en.y)
		{
			return dis[x][y];
		}

		for (int i = 0; i < 4; i++)
		{
			int xx = x + dirx[i];
			int yy = y + diry[i];
			if (xx >= 0 && xx < c && yy >= 0 && yy < r && map[xx][yy] != '#' && !vis[xx][yy])
			{
				vis[xx][yy] = true;
				dis[xx][yy] = dis[x][y] + 1;
				point pp;
				pp.x = xx;
				pp.y = yy;
				que.push(pp);
			}
		}
	}
	return -1;
}

int main()
{
	int casen;
	scanf("%d", &casen);
	while (casen--)
	{
		scanf("%d%d", &c, &r);
		char ss[10];
		gets(ss);
		for (int i = 0; i < r; i++)
		{
			cin.getline(map[i], mnx);
			map[i][c];
		}

		n = 0;
		for (int i = 0; i < r; i++)
		for (int j = 0; j < c; j++)
		{
			if (map[i][j] == 'A' || map[i][j] == 'S')
			{
				n++;
				p
.x = i;
				p
.y = j;
			}
		}

		m = 0;
		for (int i = 1; i <= n;i++)
		for (int j = i + 1; j <= n; j++)
		{
			m++;
			e[m].u = i;
			e[m].v = j;
			e[m].c = BFS(p[i], p[j]);
		}

		int ans = kruskal();
		printf("%d\n", ans);
	}
}