bzoj 2006 分类： bzoj 2015-05-31 17:18 29人阅读 评论(0) 收藏

#include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<map>
#include<string>
#include<stack>
#include<queue>
#include<utility>
#include<iostream>
#include<algorithm>

const int MAXN = 500005, logN = 20;
struct HeapNode
{
int st,ed,l,r; long long v; HeapNode(int st=0,int ed=0,int l=0,int r=0,long long v=0):st(st),ed(ed),l(l),r(r),v(v){}
};
bool operator < (const HeapNode &a,const HeapNode &b){return a.v < b.v;}

std::priority_queue<HeapNode> heap;

int n, k, L, R, seg[MAXN];
long long sum[MAXN];
long long st[MAXN][logN];
int opt[MAXN][logN];
long long ans = 0;

void PreWork()
{
for(int i = 1; i <= n; i++)
sum[i] = sum[i-1] + seg[i], st[i][0] = sum[i], opt[i][0] = i;

for(int i = 1; i < logN; i++)
{
int lmt = n - (1<<i) + 1;
for(int j = 1; j <= lmt; j++)
{
int t = j + (1<<(i-1));

if(st[j][i-1] > st[t][i-1])
st[j][i] = st[j][i-1], opt[j][i] = opt[j][i-1];
else
st[j][i] = st[t][i-1], opt[j][i] = opt[t][i-1];
}
}
}
int Ask(int a,int b)
{
int len = b - a + 1, t = 0; while((1<<(t+1)) <= len) t++;
return (st[a][t] > st[b-(1<<t)+1][t])?opt[a][t]:opt[b-(1<<t)+1][t];
}
void Insert(int st,int ll,int rr)
{
int t = Ask(ll,rr); heap.push(HeapNode(st,t,ll,rr,sum[t]-sum[st-1]));
}
void Build()
{
for(int i = 1; i + L - 1<= n; i++)
Insert(i,i+L-1,std::min(i+R-1,n));
}
void Solve()
{
for(int tp = 1; tp <= k; tp++)
{
HeapNode max = heap.top();
heap.pop();

ans += max.v;
if(max.l < max.ed) Insert(max.st,max.l,max.ed-1);
if(max.ed < max.r) Insert(max.st,max.ed+1,max.r);
}
}

int main()
{
#ifndef ONLINE_JUDGE
freopen("bzoj2006.in","r",stdin);
freopen("bzoj2006.out","w",stdout);
#endif

scanf("%d%d%d%d",&n,&k,&L,&R);
for(int i = 1; i <= n; i++) scanf("%d",&seg[i]);

PreWork();

Build();

Solve();

printf("%lld",ans);

#ifndef ONLINE_JUDGE
fclose(stdin);
fclose(stdout);
#endif
return 0;
}