【题解】 bzoj2006: [NOI2010]超级钢琴 （ST表+贪心）

题面戳我

Solution

• 不会，看的题解

Attention

• 哇痛苦，一直不会打\(ST\)表，我是真的菜啊qwq
• 预处理

  Log[1]=0;two[0]=1;
  for(int i=2;i<=n;i++)Log[i]=Log[i>>1]+1;
  for(int i=1;i<=24;i++)two[i]=two[i-1]*2;
  for(int i=1;i<=n;i++)ST[i][0]=i;
  for(int i=1;i<=24;i++){
    for(int j=0;j+two[i]<=n+1;j++){
      ST[j][i]=mina(ST[j][i-1],ST[j+two[i-1]][i-1]);
    }
  }

• 我是真的菜qwq

Code

//It is coded by ning_mew on 7.19
#include<bits/stdc++.h>
#define LL long long
using namespace std;

const int maxn=5e5+7,inf=(1<<31);

int n,k,L,R;
int Log[maxn],ST[maxn][25];
LL sum[maxn],two[25],ans=0;
struct Node{
  LL sum;int r,nl,nr,M;
  friend bool operator < (const Node &A,const Node &B){return A.sum<B.sum;}
};

priority_queue<Node>Q;

int mina(int x,int y){
  if(sum[x]<sum[y])return x;return y;
}
int quary(int x,int y){
  int kkk=Log[y-x+1];
  return mina(ST[x][kkk],ST[y-two[kkk]+1][kkk]);
}
int main(){
  scanf("%d%d%d%d",&n,&k,&L,&R);
  Log[1]=0;two[0]=1;
  for(int i=1;i<=n;i++){scanf("%lld",&sum[i]);sum[i]+=sum[i-1];}
  for(int i=2;i<=n;i++)Log[i]=Log[i>>1]+1;
  for(int i=1;i<=24;i++)two[i]=two[i-1]*2;
  for(int i=1;i<=n;i++)ST[i][0]=i;
  for(int i=1;i<=24;i++){
    for(int j=0;j+two[i]<=n;j++){
      ST[j][i]=mina(ST[j][i-1],ST[j+two[i-1]][i-1]);
    }
  }
  for(int i=L;i<=n;i++){
    int l=max(0,i-R),r=i-L;
    Node box;box.r=i;box.nl=l;box.nr=r;
    box.M=quary(l,r);box.sum=sum[i]-sum[box.M];
    Q.push(box);
  }
  while(k){
    k--;Node box=Q.top();Q.pop();
    ans+=box.sum;
    Node A,B;
    if(box.nl<box.M){
      A.nl=box.nl;A.nr=box.M-1;A.M=quary(A.nl,A.nr);
      A.r=box.r;A.sum=sum[A.r]-sum[A.M];
      Q.push(A);
    }
    if(box.M<box.nr){
      B.nl=box.M+1;B.nr=box.nr;B.M=quary(B.nl,B.nr);
      B.r=box.r;B.sum=sum[B.r]-sum[B.M];
      Q.push(B);
    }
  }printf("%lld\n",ans);
  return 0;
}

博主蒟蒻，随意转载。但必须附上原文链接：http://www.cnblogs.com/Ning-Mew/，否则你会场场比赛暴0！！！