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ACM ICPC 2018 World Finals

感谢discuss ,水过

Posted by ALLACS at 2018-01-09 14:36:38 on Problem 3026
//bfs+kruskal
#include <iostream>
#include<cstdio>
#include<algorithm>
#include<queue>
#include<cstring>
using namespace std;
typedef pair<int,int>PII;
const int maxv=110;
const int maxe=6000+5;
const int dx[]={-1,1,0,0};
const int dy[]={0,0,-1,1};
struct Edge{
int from,to,weight;
};
bool operator<(const Edge &E1,const Edge &E2)
{
    return E1.weight<E2.weight;
}
Edge edges[maxe];
int parent[maxv];
int find(int x)
{
    return x==parent[x]?x:parent[x]=find(parent[x]);
}
char str[maxv][maxv];
PII ps[maxv];
int dist[maxv][maxv];
int n,m;
void bfs(int x,int y)
{
    queue<PII>pq;
    while(!pq.empty()) pq.pop();
    pq.push(PII(x,y));
    memset(dist,-1,sizeof(dist));
    dist[x][y]=0;
    while(!pq.empty())
    {
        PII k=pq.front();
        pq.pop();
        for(int i=0;i<4;i++)
        {
            int nx=k.first+dx[i],ny=k.second+dy[i];
            if(nx>=0&&nx<m&&ny>=0&&ny<n&&str[nx][ny]!='#'&&dist[nx][ny]==-1) {
                pq.push(PII(nx,ny));
                dist[nx][ny]=dist[k.first][k.second]+1;
            }
        }
    }
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        char temp[maxv];
        scanf("%d%d",&n,&m);        //n为列数,m为行数
        gets(temp);                     //输入两个整数后有空格
        int ans=2;
        for(int i=0;i<m;i++)
        {
            gets(str[i]);
            for(int j=0;j<n;j++)
            {
                if(str[i][j]=='A') {
                    ps[ans].first=i;
                    ps[ans].second=j;
                    ans++;
                }
                else if(str[i][j]=='S') {
                           ps[1].first=i;
                           ps[1].second=j;
                }
            }
        }
        //bfs并建图
        int cnt=0;
        for(int i=1;i<ans-1;i++)
        {
            bfs(ps[i].first,ps[i].second);
            //根据dist数组建图
            for(int j=i+1;j<ans;j++)
            {
                edges[cnt].from=i;
                edges[cnt].to=j;
                edges[cnt].weight=dist[ps[j].first][ps[j].second];
                cnt++;
            }
        }
        sort(edges,edges+cnt);
        int sum=0;
        for(int i=1;i<=ans-1;i++)
            parent[i]=i;
        for(int i=0;i<cnt;i++)
        {
            int p1=find(edges[i].from);
            int p2=find(edges[i].to);
            if(p1==p2) continue;
            parent[p1]=p2;
            sum+=edges[i].weight;
        }
        printf("%d\n",sum);
    }
    return 0;
}

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