POJ 1797 Heavy Transportation（最大生成树/最短路变形）

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn = 1005;
struct Edge{
	int u,v,w;
}edge[maxn*maxn/2];
int fa[maxn];

bool cmp(Edge a,Edge b)
{
	return a.w > b.w;
}

int find(int x)
{
	return fa[x] == x?fa[x]:fa[x] = find(fa[x]);
}

void Union(int x,int y)
{
	int fx = find(x),fy = find(y);
	if (fx != fy)	fa[fx] = fy;
}

int main()
{
	int tcase;
	scanf("%d",&tcase);
	for (int t = 1;t <= tcase;t++)
	{
		int n,m,res = 0x3f3f3f3f;
		scanf("%d%d",&n,&m);
		for (int i = 0;i <= n;i++)	fa[i] = i;
		for (int i = 0;i < m;i++)
		{
			scanf("%d%d%d",&edge[i].u,&edge[i].v,&edge[i].w);
		}
		sort(edge,edge + m,cmp);
		for (int i = 0; i< m;i++)
		{
			Union(edge[i].u,edge[i].v);
			if (find(1) == find(n))
			{
				res = edge[i].w;
				break;
			}
		}
		printf("Scenario #%d:\n",t);
		printf("%d\n",res);
		if (t != tcase)	printf("\n");
	}
	return 0;
} 

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
const int maxn = 1005;
const int INF = 0x3f3f3f3f;
struct Edge{
	int u,v,w,nxt;
	bool operator < (const Edge &a)const
	{
		return w < a.w;
	}
}edge[maxn*maxn];
int tot = 0,head[maxn],dis[maxn];
bool vis[maxn];

void addedge(int u,int v,int w)
{
	edge[tot] = (Edge){u,v,w,head[u]
	};
	head[u] = tot++;
}

void dijkstra(int st,int n)
{
	Edge p;
	priority_queue<Edge>que;
	memset(dis,0,sizeof(dis));
	memset(vis,false,sizeof(vis));
	p.v = st;
	p.w = INF;
	dis[st] = INF;
	que.push(p);
	while (!que.empty())
	{
		p = que.top();
		que.pop();
		int u = p.v;
		if (vis[u])	continue;
		vis[u] = true;
		for (int i = head[u];~i;i = edge[i].nxt)
		{
			int v = edge[i].v,w = edge[i].w;
			if (dis[v] < min(dis[u],w))
			{
				dis[v] = min(dis[u],w);
				p.v = v,p.w = dis[v];
				que.push(p); 
			}
		}
	}
}


int main()
{
	int tcase;
	scanf("%d",&tcase);
	for (int t = 1;t <= tcase;t++)
	{
		int n,m,u,v,w;
		memset(head,-1,sizeof(head));
		scanf("%d%d",&n,&m);
		for (int i = 0;i < m;i++)
		{
			scanf("%d%d%d",&u,&v,&w);
			addedge(u,v,w);
			addedge(v,u,w);
		}
		dijkstra(1,n);
		printf("Scenario #%d:\n",t);
		printf("%d\n",dis[n]);
		if (t != tcase)	printf("\n");
	}
	return 0;
	
} 

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
const int maxn = 1005;
const int INF = 0x3f3f3f3f;
struct Edge{
	int u,v,w,nxt;
}edge[maxn*maxn];
int tot = 0,head[maxn],dis[maxn];
bool vis[maxn];

void addedge(int u,int v,int w)
{
	edge[tot] = (Edge){u,v,w,head[u]
	};
	head[u] = tot++;
}


void spfa(int st,int ed)
{
	memset(vis,false,sizeof(vis));
	memset(dis,0,sizeof(dis));
	queue<int>que;
	dis[st] = INF;
	que.push(st);
	vis[st] = true;
	while (!que.empty())
	{
		int u = que.front();
		que.pop();
		vis[u] = false;
		for (int i = head[u];~i;i = edge[i].nxt)
		{
			int v = edge[i].v,w = edge[i].w;
			if (min(dis[u],w) > dis[v])
			{
				dis[v] = min(dis[u],w);
				if (!vis[v])
				{
					que.push(v);
					vis[v] = true;
				}
			}
		}
	}
}

int main()
{
	int tcase;
	scanf("%d",&tcase);
	for (int t = 1;t <= tcase;t++)
	{
		int n,m,u,v,w;
		memset(head,-1,sizeof(head));
		scanf("%d%d",&n,&m);
		for (int i = 0;i < m;i++)
		{
			scanf("%d%d%d",&u,&v,&w);
			addedge(u,v,w);
			addedge(v,u,w);
		} 
		spfa(1,n);
		printf("Scenario #%d:\n",t);
		printf("%d\n",dis[n]);
		if (t != tcase)	printf("\n");
	}
}