TM终于过了。。。。
#include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #define maxv 300500 #define maxe 800500 #define inf 0x7fffffffffffffff using namespace std; struct edge { long long v,w,nxt; }e[maxe]; struct edge_mp { long long u,v,w,flag; }mp[maxe]; long long n,m,g[maxv],nume=0,father[maxv],anc[maxv][22],mx1[maxv][22],mx2[maxv][22],ans=0,dx=inf,dis[maxv]; long long r1=0,r2=0; bool cmp(edge_mp x,edge_mp y) { return x.w<y.w; } void addedge(long long u,long long v,long long w) { e[++nume].v=v; e[nume].w=w; e[nume].nxt=g[u]; g[u]=nume; } long long getfather(long long x) { if (father[x]!=x) father[x]=getfather(father[x]); return father[x]; } void kruskal() { for (long long i=1;i<=n;i++) father[i]=i; sort(mp+1,mp+m+1,cmp); for (long long i=1;i<=m;i++) { long long u=mp[i].u,v=mp[i].v,w=mp[i].w; if (getfather(u)!=getfather(v)) { father[getfather(u)]=getfather(v);mp[i].flag=1;ans+=w; addedge(u,v,w);addedge(v,u,w); } } } void dfs(long long x,long long father) { for (long long i=g[x];i;i=e[i].nxt) { long long v=e[i].v; if (v!=father) { anc[v][0]=x;mx1[v][0]=e[i].w;mx2[v][0]=0; dis[v]=dis[x]+1; dfs(v,x); } } } void get_table() { for (long long e=1;e<=20;e++) for (long long i=1;i<=n;i++) { anc[i][e]=anc[anc[i][e-1]][e-1]; long long regis[5]; regis[1]=mx1[i][e-1];regis[2]=mx1[anc[i][e-1]][e-1]; regis[3]=mx2[i][e-1];regis[4]=mx2[anc[i][e-1]][e-1]; sort(regis+1,regis+5); mx1[i][e]=regis[4]; for (long long j=3;j>=1;j--) { if (regis[j]==regis[j+1]) continue; else {mx2[i][e]=regis[j];break;} } } } void get_ans(long long x) { long long u=mp[x].u,v=mp[x].v;r1=-1;r2=-1; long long k1=-1,k2=-1,k3=-1,k4=-1; if (dis[u]<dis[v]) swap(u,v); if (dis[u]!=dis[v]) { for (long long e=20;e>=0;e--) { long long pos=anc[u][e]; if ((dis[pos]>=dis[v]) && (pos>0)) { long long regis[5]; regis[1]=mx1[u][e];regis[2]=mx2[u][e];regis[3]=k1;regis[4]=k2; sort(regis+1,regis+5); k1=regis[4]; for (long long i=3;i>=1;i--) { if (regis[i]==regis[i+1]) continue; else {k2=regis[i];break;} } u=pos; } } } if (u==v) { r1=k1;r2=k2; return; } for (long long e=20;e>=0;e--) { long long posu=anc[u][e],posv=anc[v][e]; if (posu!=posv) { long long regis[5]; regis[1]=mx1[u][e];regis[2]=mx2[u][e];regis[3]=k1;regis[4]=k2; sort(regis+1,regis+5); k1=regis[4]; for (long long i=3;i>=1;i--) { if (regis[i]==regis[i+1]) continue; else {k2=regis[i];break;} } regis[1]=mx1[v][e];regis[2]=mx2[v][e];regis[3]=k3;regis[4]=k4; sort(regis+1,regis+5); k3=regis[4]; for (long long i=3;i>=1;i--) { if (regis[i]==regis[i+1]) continue; else {k4=regis[i];break;} } u=posu;v=posv; } } long long regis[8]; regis[1]=k1;regis[2]=k2;regis[3]=k3;regis[4]=k4;regis[5]=mx1[u][0];regis[6]=mx1[v][0]; sort(regis+1,regis+7); r1=regis[6]; for (long long i=5;i>=1;i--) { if (regis[i]==regis[i+1]) continue; else {r2=regis[i];break;} } } int main() { scanf("%lld%lld",&n,&m); for (long long i=1;i<=m;i++) { scanf("%lld%lld%lld",&mp[i].u,&mp[i].v,&mp[i].w); mp[i].flag=0; } kruskal(); memset(mx1,0,sizeof(mx1)); memset(mx2,0,sizeof(mx2)); dfs(1,1); get_table(); for (long long i=1;i<=m;i++) { if (mp[i].flag) continue; long long u=mp[i].u,v=mp[i].v,w=mp[i].w; get_ans(i); if (r1==mp[i].w) { if (r2==-1) continue; dx=min(dx,mp[i].w-r2); } else if (r1<mp[i].w) dx=min(dx,mp[i].w-r1); } printf("%lld ",ans+dx); return 0; }