poj3159candies

差分约束

建图，求1到n最短路

要用栈spfa，否则会TLE。
#include<stdio.h>
#include<string.h>
#include<queue>
#include<algorithm>
using namespace std;
typedef long long ll;
struct node
{
ll to,next,len;
}edge[150005];
ll head[150005];
ll cnt;
void add(ll f,ll t,ll l)
{
edge[cnt].to=t;
edge[cnt].len=l;
edge[cnt].next=head[f];
head[f]=cnt++;
}
ll n,m;
ll vis[150005];
ll dis[150005];
ll spfa()
{
ll que[150005];
memset(vis,0,sizeof(vis));
memset(dis,0x3f,sizeof(dis));
dis[1]=0;
vis[1]=1;
que[1]=1;
ll tot=1;
while(tot!=0)
{
ll u=que[tot--];
vis[u]=0;
for(ll i=head[u];i!=-1;i=edge[i].next)
{
ll v=edge[i].to;
if(dis[v]>dis[u]+edge[i].len)
{
dis[v]=dis[u]+edge[i].len;
if(vis[v]==0)
{
vis[v]=1;
que[++tot]=v;
}
}
}
}
return dis
;
}
int main()
{
while(scanf("%lld %lld",&n,&m)!=EOF)
{
cnt=0;
memset(head,-1,sizeof(head));
for(ll i=1;i<=m;i++)
{
ll a,b,c;
scanf("%lld %lld %lld",&a,&b,&c);
add(a,b,c);
}
printf("%lld\n",spfa());
}
}