bzoj3538[Usaco2014 Open]Dueling GPS*

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <queue>
 5 #define inc(i,j,k) for(int i=j;i<=k;i++)
 6 #define maxn 10010
 7 #define INF 0x3fffffff
 8 using namespace std;
 9 
10 inline int read(){
11     char ch=getchar(); int f=1,x=0;
12     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1; ch=getchar();}
13     while(ch>=‘0‘&&ch<=‘9‘)x=x*10+ch-‘0‘,ch=getchar();
14     return f*x;
15 }
16 struct e{int f,t,w,n;}es[maxn*5]; int g[maxn],ess;
17 void pe(int f,int t,int w){es[++ess]=(e){f,t,w,g[f]}; g[f]=ess;}
18 int n,m,a[2][maxn*5],b[maxn*5],d[2][maxn]; queue<int>q; bool inq[maxn];
19 void spfa(int s,int o){
20     while(!q.empty())q.pop(); memset(inq,0,sizeof(inq)); inc(i,1,n)d[o][i]=INF;
21     q.push(s); inq[s]=1; d[o][s]=0;
22     while(!q.empty()){
23         int x=q.front(); q.pop(); inq[x]=0;
24         for(int i=g[x];i;i=es[i].n)if(d[o][x]+es[i].w<d[o][es[i].t]){
25             d[o][es[i].t]=d[o][x]+es[i].w; if(!inq[es[i].t])q.push(es[i].t),inq[es[i].t]=1;
26         }
27     }
28 }
29 int main(){
30     n=read(); m=read(); inc(i,1,m){int x=read(),y=read(),z=read(); pe(y,x,z); a[0][i]=z; a[1][i]=read();}
31     spfa(n,0); inc(i,1,m)es[i].w=a[1][i]; spfa(n,1);
32     inc(i,1,m){inc(j,0,1)if(d[j][es[i].f]+a[j][i]>d[j][es[i].t])b[i]++; es[i].w=b[i];}
33     spfa(n,0); printf("%d",d[0][1]); return 0;
34 }