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最新推荐文章于 2022-07-02 17:25:34 发布

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最新推荐文章于 2022-07-02 17:25:34 发布

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原文链接：http://www.cnblogs.com/Felix-F/archive/2013/05/23/3094235.html

POJ 2485 自制prim 模版复杂度O(ElogE) 优先队列优化

#include <queue>
#include <stack>
#include <cstdio>
#include <cstring>
#include <vector>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
#define MAXN 1000
#define MAXE 1000000
#define INF  0x3f3f3f3f
#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))
struct Edge{
    int u,v,w; // start,end,value
    int next;
}edge[MAXE];
int head[MAXN];
int cnt,n,m;
bool vis[MAXN];
int father[MAXN];
bool operator < (Edge a, Edge b){
    return a.w > b.w;
}
void add(Edge x){ // add edge to the list
    edge[cnt].u = x.u;
    edge[cnt].v = x.v;
    edge[cnt].w = x.w;
    edge[cnt].next = head[x.u];
    head[x.u] = cnt++;
//    edge[cnt].v = x.u;
//    edge[cnt].u = x.v;
//    edge[cnt].w = x.w;
//    edge[cnt].next = head[x.v];
//    head[x.v] = cnt++;
}
int prim(int u){
    int ans = -1;
    priority_queue<Edge> q;
    vector<int> vec;
    memset(vis,0,sizeof(vis));
    for(int i = head[u]; i != -1; i = edge[i].next)
        q.push(edge[i]);
    vec.push_back(u);
    vis[u] = 1;
    while(vec.size() != n)
    {
        if(vis[q.top().u] && vis[q.top().v]){
            q.pop();
            continue;
        }
        ans += q.top().w;
        int t = vis[q.top().u] ? q.top().v : q.top().u;
        q.pop();
        vec.push_back(t);
        vis[t] = 1;
        for(int i = head[t]; i != -1; i = edge[i].next)
            if(!vis[edge[i].v])
                q.push(edge[i]);
    }
    cout<<ans<<endl;
}
int main(){
  //freopen("in.txt","r",stdin);
    int T;
    cin>>T;
    while(T--){
        scanf("%d",&n);
        memset(edge,0,sizeof(edge));
        memset(head,-1,sizeof(head));
        Edge tmp;
        cnt = 0;
        int a;
        for(int i = 1 ; i <= n; i++ ){
            for(int j = 1 ; j <= n ; j++){
                scanf("%d",&a);
                if(a) {
                    tmp.u = i;
                    tmp.v = j;
                    tmp.w = a;
                    add(tmp);
                }
            }
        }
        prim(1);
    }
    return 0;
}