?
# | Author | Problem | Lang | Verdict | Time | Memory | Sent | Judged | |
---|---|---|---|---|---|---|---|---|---|
87750686 |
Practice: luogu_bot4 |
835F - 34 | GNU C++11 | Accepted | 140 ms | 32276 KB | 2020-07-23 11:46:27 | 2020-07-23 11:46:27 |
#include<bits/stdc++.h> #define int long long using namespace std; const int N=200005,INF=1e18+5; struct edge{ int to,wei,nxt; }e[N<<1]; int n,tot=0,cnt=0,ans1=0,ans2=INF,res,head[N],cir[N],vis[N],f[N],we[N],l[N],l0[N],r[N],r0[N]; inline void adde(int x,int y,int w) { e[++tot]=(edge){y,w,head[x]}; head[x]=tot; } inline int fnd(int x,int fa=-1) { if(vis[x]) return x; else vis[x]=-1; for(int i=head[x];i;i=e[i].nxt) { if(e[i].to!=fa) { res=fnd(e[i].to,x); if(res) { cir[++cnt]=x; we[cnt]=e[i].wei; vis[x]=1; if(res==x) return 0; return res; } } } return 0; } inline void dfs(int x,int fa=-1) { for(int i=head[x];i;i=e[i].nxt) { if(vis[e[i].to]!=1&&e[i].to!=fa) { dfs(e[i].to,x); ans1=max(ans1,f[x]+f[e[i].to]+e[i].wei); f[x]=max(f[x],f[e[i].to]+e[i].wei); } } } signed main() { scanf("%lld",&n); for(int i=1,x,y,w;i<=n;i++) { scanf("%lld%lld%lld",&x,&y,&w); adde(x,y,w); adde(y,x,w); } fnd(1); we[0]=0; for(int i=1;i<=cnt;i++) { dfs(cir[i]); we[i]+=we[i-1]; } res=l[0]=l0[0]=-INF; for(int i=1;i<=cnt;i++) { l0[i]=max(l0[i-1],f[cir[i]]+we[i]+res); l[i]=max(l[i-1],f[cir[i]]+we[i]); res=max(res,f[cir[i]]-we[i]); } res=r[cnt+1]=r0[cnt+1]=-INF; for(int i=cnt;i>=1;i--) { r0[i]=max(r0[i+1],f[cir[i]]-we[i]+res); r[i]=max(r[i+1],f[cir[i]]+we[cnt]-we[i]); res=max(res,f[cir[i]]+we[i]); } for(int i=1;i<=cnt;i++) { ans2=min(ans2,max(l[i-1]+r[i],max(l0[i-1],r0[i]))); } printf("%lld\n",max(ans1,ans2)); return 0; }
?
?
?
?