[分块 暴力 树] BZOJ 4381 [POI2015]Odwiedziny

大概就是步数小的预处理前缀和

步数大的直接倍增跳

各种细节搞得欲仙欲死

#include<cstdio>#include<cstdlib>#include<algorithm>#include<cstring>#include<cmath>using namespace std;typedef long long ll;inline char nc(){  static char buf[100000],*p1=buf,*p2=buf;  if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); if (p1==p2) return EOF; }  return *p1++;}inline void read(int &x){  char c=nc(),b=1;  for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;  for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;}const int N=50005;const int K=21;const int M=305;struct edge{  int u,v,next;}G[N<<1];int head[N],inum;inline void add(int u,int v,int p){  G[p].u=u; G[p].v=v; G[p].next=head[u]; head[u]=p;}int n,B; ll ans;int val[N],bp[N];int depth[N],fat[N][K];ll S[N][M];#define V G[p].vinline void dfs(int u,int fa){  depth[u]=depth[fa]+1; fat[u][0]=fa;  for (int k=1;k<K;k++)    fat[u][k]=fat[fat[u][k-1]][k-1];  int f=fa;  for (int i=1;i<=B;i++)    S[u][i]=S[f][i]+val[u],f=fat[f][0];  for (int p=head[u];p;p=G[p].next)    if (V!=fa)      dfs(V,u);}inline int LCA(int u,int v){  if (depth[u]<depth[v]) swap(u,v);  for (int k=K-1;~k;k--)    if ((depth[u]-depth[v])>>k&1)      u=fat[u][k];  if (u==v) return u;  for (int k=K-1;~k;k--)    if (fat[u][k]!=fat[v][k])      u=fat[u][k],v=fat[v][k];  return fat[u][0];}inline int Fat(int u,int s){  for (int k=K-1;~k;k--)    if (s>>k&1)      u=fat[u][k];  return u;}inline ll Solve(int u,int v,int cp){  int lca=LCA(u,v),len=depth[u]+depth[v]-2*depth[lca],t,l1,l2;  ll ret=0;  if (len<=cp) return val[u]+val[v];  if (cp>B){    ret+=val[u];    while (1){      t=Fat(u,cp);      if (depth[t]>=depth[lca])ret+=val[t],u=t;      elsebreak;    }    if (v!=lca){      ret+=val[v];      if (len%cp){v=Fat(v,len%cp);if (depth[v]>depth[lca])  ret+=val[v];      }      while (1){t=Fat(v,cp);if (depth[t]>depth[lca])  ret+=val[t],v=t;else  break;      }      return ret;    }else{      if (len%cp) ret+=val[v];      return ret;    }  }  if (u==lca)    ret+=val[lca];  else{    l1=((depth[u]-depth[lca])/cp+1)*cp;    t=Fat(u,l1);    ret+=S[u][cp]-S[t][cp];  }  if (v!=lca){    if (len%cp)      ret+=val[v],v=Fat(v,len%cp);    if (depth[v]<=depth[lca]) return ret;    l2=((depth[v]-depth[lca]-1)/cp+1)*cp;    t=Fat(v,l2);    ret+=S[v][cp]-S[t][cp];  }  else{    if (len%cp)      ret+=val[v];  }  return ret;}int main(){  int iu,iv,ic;  freopen("t.in","r",stdin);  freopen("t.out","w",stdout);  read(n); B=min(n,(int)(sqrt(n)/log(n)+1));  for (int i=1;i<=n;i++)    read(val[i]);  for (int i=1;i<n;i++)    read(iu),read(iv),add(iu,iv,++inum),add(iv,iu,++inum);  dfs(1,0);  for (int i=1;i<=n;i++)    read(bp[i]);  for (int i=1;i<n;i++)    read(ic),printf("%lld\n",Solve(bp[i],bp[i+1],ic));  return 0;}