HDU - 6386 Age of Moyu (双端队列+bfs)

题目链接

双端队列跑边，颜色相同的边之间的花费为0，放进队首；不同的花费为1，放进队尾。

用Dijkstra+常数优化也能过

 #include<bits/stdc++.h>
 using namespace std;
 typedef long long ll;
 const int N=4e5+,mod=1e9+;
 int n,m,hd[N],ne,dp[N];
 struct E {int v,c,nxt;} e[N];
 void addedge(int u,int v,int c) {e[ne]= {v,c,hd[u]},hd[u]=ne++;}
 deque<int> q;
 int solve() {
     q.clear();
     memset(dp,-,sizeof dp);
     q.push_back(ne-),dp[ne-]=;
     while(q.size()) {
         int u=q.front(),now=dp[u],cu=e[u].c;
         q.pop_front();
         if(e[u].v==n)return now;
         for(int v=hd[e[u].v]; ~v; v=e[v].nxt) {
             int cv=e[v].c;
             if(!~dp[v]) {
                 if(cv==cu)dp[v]=now,q.push_front(v);
                 else dp[v]=now+,q.push_back(v);
             }
         }
     }
     return -;
 }
 int main() {
     while(scanf("%d%d",&n,&m)==) {
         memset(hd,-,sizeof hd),ne=;
         while(m--) {
             int u,v,c;
             scanf("%d%d%d",&u,&v,&c);
             addedge(u,v,c);
             addedge(v,u,c);
         }
         addedge(,,);
         printf("%d\n",solve());
     }
     return ;
 }