【POJ 3026】Borg Maze

【POJ 3026】Borg Maze

一个考察队搜索alien 这个考察队可以无限分割 问搜索到所有alien所需要的总步数 即求一个无向图 包含所有的点并且总权值最小(最小生成树

BFS+最小生成树

Prim/Kruskal…懒死了 就这么贴吧……凑活看(￣┰￣*)

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <algorithm>
#define INF 0x3f3f3f3f

using namespace std;

typedef struct Point
{
    int x,y;
}Point;

typedef struct Edge
{
    int u,v,w;
    bool operator < (const struct Edge a)const
    {
        return w < a.w;
    }
}Edge;

Edge eg[10100];
bool vs[101][101];
Point p[101];
char mp[51][52];
int id[51][51];
int dis[101][101];
bool vis[51][51];
//int dss[101];
//bool vs[101];
int dirx[] = { 0, 0, 1,-1};
int diry[] = { 1,-1, 0, 0};
int ds[51][51];
int tp,x,y,top;
int pre[101];

void Bfs(int xx,int yy)
{
    memset(vis,0,sizeof(vis));
    queue <pair<int,int> > q;
    q.push(pair<int,int> (xx,yy));
    vis[xx][yy] = 1;
    ds[xx][yy] = 0;
    int i,aa,bb,a,b;
    while(!q.empty())
    {
        pair <int,int> pt = q.front();
        q.pop();
        a = pt.first;
        b = pt.second;
        for(i = 0; i < 4; ++i)
        {
            aa = a+dirx[i];
            bb = b+diry[i];
            if(aa > x || bb > y || aa < 1 || bb < 1 || mp[aa][bb] == ‘#‘ || vis[aa][bb]) continue;
            ds[aa][bb] = ds[a][b]+1;
            vis[aa][bb] = 1;
            q.push(pair<int,int> (aa,bb));
//            if(mp[aa][bb] != ‘ ‘) dis[id[xx][yy]][id[aa][bb]] = dis[id[aa][bb]][id[xx][yy]] = ds[aa][bb];
            if(mp[aa][bb] != ‘ ‘ && !vs[id[xx][yy]][id[aa][bb]])
            {
                vs[id[xx][yy]][id[aa][bb]] = vs[id[aa][bb]][id[xx][yy]] = 1;
                eg[top].u = id[xx][yy];
                eg[top].v = id[aa][bb];
                eg[top++].w = ds[aa][bb];
            }
        }
    }
}

void Init(int n)
{
    int i;
    for(i = 0; i < n; ++i)
        pre[i] = i;
}

int Find(int x)
{
    if(x != pre[x]) pre[x] = Find(pre[x]);
    return pre[x];
}

//int Prim()
//{
//    memset(vs,0,sizeof(vs));
//    memset(dss,INF,sizeof(dss));
//    dss[0] = 0;
//    int i,j,p,w,sum = 0;
//    for(i = 0; i < tp; ++i)
//    {
//        w = INF;
//        for(j = 0; j < tp; ++j)
//        {
//            if(!vs[j] && w > dss[j])
//            {
//                w = dss[j];
//                p = j;
//            }
//        }
//        sum += w;
//        vs[p] = 1;
//        for(j = 0; j < tp; ++j)
//        {
//            if(!vs[j] && dss[j] > dis[p][j])
//                dss[j] = dis[p][j];
//        }
//    }
//    return sum;
//}

int main()
{
    int n,i,j;
    int cnt,sum,k,r;
    scanf("%d",&n);
    while(n--)
    {
        memset(vs,0,sizeof(vs));
        tp = top = 0;
        scanf("%d %d",&y,&x);
        gets(mp[0]);
        for(i = 1; i <= x; ++i)
        {
            gets(mp[i]+1);
            for(j = 1; mp[i][j]; ++j)
            {
                if(mp[i][j] != ‘#‘ && mp[i][j] != ‘ ‘)
                {
                    id[i][j] = tp;
                    p[tp].x = i;
                    p[tp++].y = j;
                }
            }
        }
        Init(tp);
        for(i = 0; i < tp; ++i)
        {
            Bfs(p[i].x,p[i].y);
        }
//        printf("%d\n",Prim());
        sort(eg,eg+top);
        sum = cnt = 0;
        for(i = 0; i < top; ++i)
        {
            k = Find(eg[i].u);
            r = Find(eg[i].v);
            if(k != r)
            {
                pre[k] = r;
                sum += eg[i].w;
                cnt++;
            }
            if(cnt == tp) break;
        }
        printf("%d\n",sum);
    }
    return 0;
}