POJ T1797 Heavy Transportation

                       POJ T1797 Heavy Transportation

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题目思路：

    因为给的是边，所以就没犹豫用了Spfa，模板裸题.......

 

Spfa写法

#include<cstdio>
#include<algorithm>
#include<queue>
#include<cstring>
#define maxn 1005
#define INF 0x3f3f3f3f
using namespace std;

bool vis[maxn];
int dis[maxn],head[maxn],n,m,cnt;

struct Edge{
	int to,w,next;
}edge[maxn*maxn];

void Init(){
	cnt = 0;
	for(int i = 1; i <= n; i++){
		vis[i] = false;
		dis[i] = 0;
		head[i] = -1;
	}
}

void add(int from,int to,int w){
	edge[cnt].to = to;
	edge[cnt].w = w;
	edge[cnt].next = head[from];
	head[from] = cnt++; 
}

void Spfa(int s){
	int u;
	queue<int> Q;
	Q.push(s);
	vis[s] = true;
	dis[s] = INF;
	while(!Q.empty()){
		u = Q.front();
		Q.pop();           //注意出队列 
		vis[u] = false;
		for(int i = head[u]; i != -1; i = edge[i].next){
			int v = edge[i].to;    //
			int w = edge[i].w;     //这两处用i是指与U相连的边 
			if(dis[v] < min(dis[u],w)){
				dis[v] = min(dis[u],w);
				if(!vis[v]){
					Q.push(v);
					vis[v] = true;
				}
			}
		}
	}
}

int main(){
	int u,v,w,t,kcase = 0;
	scanf("%d",&t);
	while(t--){
		scanf("%d%d",&n,&m);
		Init();
		for(int i = 0; i < m; i++){
			scanf("%d%d%d",&u,&v,&w);
			add(u,v,w);
			add(v,u,w);
		}
		Spfa(1);
		printf("Scenario #%d:\n",++kcase);
		printf("%d\n\n",dis[n]);
	}
	return 0;
}