多源最短路问题

数据范围1e5

具体看代码吧

#include<cmath>
#include<ctime>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<complex>
#include<iostream>
#include<algorithm>
#include<iomanip>
#include<vector>
#include<string>
#include<bitset>
#include<queue>
#include<map>
#include<set>

using namespace std;

typedef long long ll;

inline int read()
{
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch<='9'&&ch>='0'){x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
return x*f;
}
void print(int x)
{if(x<0)putchar('-'),x=-x;if(x>=10)print(x/10);putchar(x%10+'0');}

const int N=200100,inf=0X3f3f3f3f;

int ecnt,last
;
struct EDGE{int to,nt,val;}e[N<<6];
inline void add(int u,int v,int val)
{e[++ecnt]=(EDGE){v,last[u],val};last[u]=ecnt;}

int n,m,K;

ll ans;

bool book
,inq
;

ll dis
[2],pre
[2];

int q
;

void spfa()
{
register int head=0,tail=0,i,j,u;
memset(dis,0X3f,sizeof(dis));
for(i=1;i<=n;++i)if(book[i])
{
for(j=last[i];j;j=e[j].nt)add(i+n,e[j].to,e[j].val);
dis[i+n][0]=0;pre[i+n][0]=i;q[tail++]=i+n;inq[i+n]=1;
}
while(head<tail)
{
u=q[head++];inq[u]=0;
for(i=last[u];i;i=e[i].nt)
{
if(dis[e[i].to][0]>dis[u][0]+e[i].val)
{
if(pre[e[i].to][0]^pre[u][0])
{
dis[e[i].to][1]=dis[e[i].to][0];
pre[e[i].to][1]=pre[e[i].to][0];
}
dis[e[i].to][0]=dis[u][0]+e[i].val;
pre[e[i].to][0]=pre[u][0];
if(!inq[e[i].to])q[tail++]=e[i].to,inq[e[i].to]=1;
}
else if(dis[e[i].to][1]>dis[u][0]+e[i].val&&pre[e[i].to][0]^pre[u][0])
{
dis[e[i].to][1]=dis[u][0]+e[i].val;
pre[e[i].to][1]=pre[u][0];
if(!inq[e[i].to])q[tail++]=e[i].to,inq[e[i].to]=1;
}
if(dis[e[i].to][1]>dis[u][1]+e[i].val&&pre[e[i].to][0]^pre[u][1])
{
dis[e[i].to][1]=dis[u][1]+e[i].val;
pre[e[i].to][1]=pre[u][1];
if(!inq[e[i].to])q[tail++]=e[i].to,inq[e[i].to]=1;
}
}
}
for(i=1;i<=n;++i)if(book[i])
{pre[i][0]^i?ans=min(ans,dis[i][0]):ans=min(ans,dis[i][1]);}
}

int main()
{
n=read();m=read();K=read();
register int i,u,v,val;
for(i=1;i<=m;++i){u=read();v=read();val=read();add(u,v,val);}
for(i=1;i<=K;++i)book[read()]=1;
ans=inf;spfa();
print(ans);puts("");
return 0;
}
/*
5 10 3
3 4 30
3 5 29
1 5 55
4 5 52
1 3 48
2 4 36
2 5 10
1 4 47
2 3 30
1 2 19
1 3 4

30
*/