POJ 1511

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
using namespace std;
#define N 1000000+100
#define inf 1000000000+10
typedef long long ll;

struct Edge
{
int to,v;
int next;
}edge1
,edge2
;
int head1
,head2
,book
,strk
;
ll go
,backk
;
ll spfa(Edge *edge,ll *go,int *head,int n);
void Insert(Edge *edge,int *head,int a,int b,int v,int i);
int main()
{
int n,m,i,j,k,t;
scanf("%d",&t);
while(t--)
{
scanf("%d%d",&n,&m);
memset(head1,-1,(n+10)*sizeof(n));
memset(head2,-1,(n+10)*sizeof(n));
int a,b,v;
for(i=1; i<=m; i++)
{
scanf("%d%d%d",&a,&b,&v);
Insert(edge1,head1,a,b,v,i);
Insert(edge2,head2,b,a,v,i);
}
for(i=1; i<=n; i++)
go[i] = inf , backk[i] = inf;
printf("%lld\n",spfa(edge1,go,head1,n)+spfa(edge2,backk,head2,n));
}

}
void Insert(Edge *edge,int *head,int a,int b,int v,int i)
{
edge[i].to = b;
edge[i].v = v;
edge[i].next = head[a];
head[a] = i;
}
ll spfa(Edge *edge,ll *go,int *head,int n)
{
memset(book,0,sizeof(book));
go[1] = 0 , book[1] = 1;
int top = 0;
strk[++top] = 1;
while(top)
{
int u = strk[top--];
book[u] = 0;
int t = head[u];
while(t != -1)
{
int a = edge[t].to;
int v = edge[t].v;
if(go[a] > go[u] + v)
{
go[a] = go[u] + v;
if(book[a] == 0)
book[a] = 1 , strk[++top] = a;
}
t = edge[t].next;
}
}
ll sum = 0;
for(int i=1; i<=n; i++)
sum += go[i];
return sum;
}