Bzoj 1564 [NOI2009] binary search tree (tree dp)

"Topic link"

http://www.lydsy.com/JudgeOnline/problem.php?id=1564

Test instructions

Given a treap, the total cost is the sum of the depth * distance. You can modify the weights at the cost of K, asking the minimum price.

Ideas

The data values are constant, so the treap traversal is unique. First, the data is sorted by data value, and the sequential traversal is obtained.

The weights are then discretized into the [1,n] range.

Set F[L][R][W] for the interval [l,r] The weight of the value is greater than w when the minimum cost, there is a transfer type:

f[l][r][w]=min {f[l][k-1][w]+f[k+1][r][w]+k+c (l,r)},a[k].w>=w

f[l][r][w]=min {f[l][k-1][a[k].w]+f[k+1][r][a[k].w]+c (l,r)}

Memory Search Better Write Lalala

Code

1#include <Set>2#include <cmath>3#include <queue>4#include <vector>5#include <cstdio>6#include <cstring>7#include <iostream>8#include <algorithm>9 #defineTrav (u,i) for (int i=front[u];i;i=e[i].nxt)Ten #definefor (A,B,C) for (int a= (b); a<= (c); a++) One using namespacestd; A  -typedefLong Longll; - Const intN = the; the Const intINF =1e9; -  - structNode - { +     intdat,w,c; -     BOOL operator< (Constnode& RHS)Const  +     { A         returndat<Rhs.dat; at     } - } A[n]; -  - intN,k,sumc[n],f[n][n][n]; -pair<int,int>B[n]; -  in intdpintLintRintW) - { to     int& ans=F[l][r][w]; +     if(L>r)returnans=0; -     if(ans!=-1)returnans; theans=inf; * For (k,l,r) { $         if(a[k].w>=W)Panax NotoginsengAns=min (ANS,DP (l,k-1, A[K].W) +DP (k +1, R,A[K].W) +sumc[r]-sumc[l-1]); -Ans=min (ANS,DP (l,k-1, W) +DP (k +1, r,w) +sumc[r]-sumc[l-1]+K); the     } +     returnans; A } the  + intMain () - { $ //freopen ("in.in", "R", stdin); $ //freopen ("Out.out", "w", stdout); -memset (f,-1,sizeof(f)); -scanf"%d%d",&n,&K); thefor (I,1, N) scanf ("%d",&a[i].dat); -for (I,1, N) scanf ("%d",&A[I].W);Wuyifor (I,1, N) scanf ("%d",&a[i].c); theSort (A +1, a+n+1); -for (I,1, N) Wub[i]=Make_pair (a[i].w,i); -Sort (b +1, b+n+1); Aboutfor (I,1, N) $a[b[i].second].w=I, -sumc[i]=sumc[i-1]+a[i].c; -      -     intans=inf; Afor (I,1, N) +Ans=min (ANS,DP (1, N,i)); theprintf"%d", ans); -     return 0; $}

Bzoj 1564 [NOI2009] binary search tree (tree dp)