Hdu_5788_level Up (tree-like array + chairman tree)

Topic Link: hdu_5788_level up

Test instructions

There is a tree, n nodes, each node has a capability value a[i],mid[i],mid The median of the sub-tree of the I node (including itself), and now lets you change one of the nodes to a value of 1e5, asking all of the mid's and the maximum number of questions.

Exercises

We can know that if you change one of the a[i], if a[i] is smaller than the mid of his father's node, then the median of his father's time will be shifted back one

For example, 1 2 3 4 5, the 3rd point is the 2nd point of the Father, if changed the second point of a value, then it becomes 1 3 4 5 1e5, the second point of the father's mid has become 4, compared to a backward move.

So we can use the Chair tree to support querying the median, and then preprocess the values of mid and mid+1 for each node.

Finally, a tree-like array +dfs is used to maintain a maximum difference.

1#include <bits/stdc++.h>2 #defineF (I,A,B) for (int i=a;i<=b;i++)3 using namespacestd;4typedefLong Longll;5 6 Const intn=1e5+7, p=1e5;7 intA[n],n,g[n],v[n],nxt[n],ed,x,tot,root[n],dfn[n],dfs_idx,sz[n],mid[n],val[n];8 ll Sum[n],ans,mx;9 TenInlinevoidAdgintXintY) {v[++ed]=y,nxt[ed]=g[x],g[x]=Ed;} One voidInit () {ed=tot=dfs_idx=0, ans=mx=0; memset (SUM,0,sizeof(sum)); Memset (G,0,sizeof(g));} AInlinevoidUpmax (ll &a,ll b) {if(a<b) a=b;} - //------------------A tree-like array -InlinevoidAddintXintc) { while(x<=p) sum[x]+=c,x+=x&-x;} theinline LL Ask (intx) {ll an=0; while(x) an+=sum[x],x-=x&-x;returnan ;} - //------------------Chairman Tree - structnode{intL,r,sum;} t[n* -]; -  +InlinevoidUpdateint&x,intYintPosintL=1,intR=P) - { +t[++tot]=t[y],t[tot].sum++,x=tot; A     if(L==R)return; at     intM=l+r>>1; -     if(pos<=m) update (T[X].L,T[Y].L,POS,L,M); -     ElseUpdate (t[x].r,t[y].r,pos,m+1, R); - } -  -InlineintQueryintXintYintKintL=1,intR=P) in { -     if(L==R)returnl; to     intM=l+r>>1, sum=t[t[x].l].sum-t[t[y].l].sum; +     if(k<=sum)returnquery (t[x].l,t[y].l,k,l,m); -     Else returnQuery (t[x].r,t[y].r,k-sum,m+1, R); the } *  $ voidPredfs (intu=1)Panax Notoginseng { -sz[u]=1, dfn[u]=++Dfs_idx; theUpdate (root[dfn[u]],root[dfn[u]-1],a[u]); +      for(intI=g[u];i;i=nxt[i]) Predfs (V[i]), sz[u]+=Sz[v[i]]; A     if(!g[u]) mid[u]=a[u],val[u]=p-a[u],ans+=A[u]; the     Else +     { -         ints=sz[u]+1>>1; $Mid[u]=query (root[dfs_idx],root[dfn[u]-1],s); $Val[u]=query (root[dfs_idx],root[dfn[u]-1],s+1)-Mid[u]; -ans+=Mid[u]; -     } the } - Wuyi voidDfsintu=1) the { - Add (Mid[u],val[u]); WuUpmax (Mx,ask (P)-ask (a[u]-1)); -      for(intI=g[u];i;i=Nxt[i]) DFS (v[i]); AboutAdd (mid[u],-Val[u]); $ } -  - intMain () - { A      while(~SCANF ("%d",&N)) +     { the init (); -F (I,1, N) scanf ("%d", A +i); $F (I,2, N) scanf ("%d",&x), ADG (x,i); the Predfs (), DFS (); theprintf"%lld\n", ans+MX); the     } the     return 0; -}

View Code

Hdu_5788_level Up (tree-like array + chairman tree)