http://acm.timus.ru/problem.aspx?space=1&num=1160
最短路变形 水题 spfa
代码:
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<map>
#include<queue>
#include<stack>
#include<cmath>
#define LL long long
//#pragma comment(linker, "/STACK:1024000000,1024000000")
using namespace std;
const int INF=0x3f3f3f3f;
const int N=1005;
const int M=30005;
int head[N],I;
struct node
{
int j,next,v;
}side[M];
int f[N];
void Add(int i,int j,int v)
{
side[I].j=j;
side[I].v=v;
side[I].next=head[i];
head[i]=I++;
}
int spfa(int s,int n)
{
int dist[N];
bool in[N];
for(int i=1;i<=n;++i)
dist[i]=INF;
dist[1]=0;
memset(in,false,sizeof(in));
queue<int>qt;
qt.push(s);
in[s]=true;
while(!qt.empty())
{
int x=qt.front();qt.pop();
in[x]=false;
for(int t=head[x];t!=-1;t=side[t].next)
{
int l=side[t].j;
if(dist[l]>max(dist[x],side[t].v))
{
dist[l]=max(dist[x],side[t].v);
f[l]=x;
if(!in[l])
{
in[l]=true;
qt.push(l);
}
}
}
}
int k=0;
for(int i=1;i<=n;++i)
k=max(k,dist[i]);
return k;
}
int main()
{
//freopen("data.txt","r",stdin);
int n,m;
while(scanf("%d %d",&n,&m)!=EOF)
{
memset(head,-1,sizeof(head));
I=0;
while(m--)
{
int a,b,c;
scanf("%d %d %d",&a,&b,&c);
Add(a,b,c);
Add(b,a,c);
}
printf("%d\n",spfa(1,n));
printf("%d\n",n-1);
for(int i=2;i<=n;++i)
printf("%d %d\n",f[i],i);
}
return 0;
}
转载于:https://www.cnblogs.com/liulangye/archive/2012/10/25/2739095.html