正题

题目链接:https://www.luogu.com.cn/problem/P3466

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题目大意

$n$个数，每次可以让一个$+1$或$-1$，要求操作次数最少使得有连续$k$个相同的。

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解题思路

枚举是哪$k$个，然后用平衡树（或对顶堆）维护中位数和比中位数小的值，这里平衡树写的少就直接用$Treap$维护了。

时间复杂度$O(n\log n)$

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$code$

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#define ll long long
using namespace std;
const ll N=1e5+10;
ll n,k,tot,rt,a[N],dat[N],sum[N],siz[N],cnt[N],t[N][2],w[N];
void PushUp(ll x){sum[x]=sum[t[x][0]]+sum[t[x][1]]+w[x]*cnt[x];siz[x]=siz[t[x][0]]+siz[t[x][1]]+cnt[x];return;
}
void zig(ll &x){ll y=t[x][0];t[x][0]=t[y][1];t[y][1]=x;x=y;PushUp(t[y][1]);PushUp(y);return;
}
void zag(ll &x){ll y=t[x][1];t[x][1]=t[y][0];t[y][0]=x;x=y;PushUp(t[y][0]);PushUp(y);return;
}
void Insert(ll &x,ll val,ll k){if(!x){x=++tot;dat[x]=rand();w[x]=sum[x]=val;siz[x]=cnt[x]=1;return;}else if(val==w[x]){cnt[x]+=k;PushUp(x);return;}if(val<w[x]){Insert(t[x][0],val,k);if(dat[x]>dat[t[x][0]])zig(x);}else{Insert(t[x][1],val,k);if(dat[x]>dat[t[x][1]])zag(x);}PushUp(x);return;
}
ll GetVal(ll x,ll k,ll &S){if(k<=siz[t[x][0]])return GetVal(t[x][0],k,S);S+=sum[x]-sum[t[x][1]];if(k<=siz[x]-siz[t[x][1]]){int z=siz[x]-siz[t[x][1]]-k;S-=w[x]*z;return w[x];}return GetVal(t[x][1],k-siz[x]+siz[t[x][1]],S);
}
int main()
{srand(19260817);scanf("%lld%lld",&n,&k);for(ll i=1;i<=n;i++)scanf("%lld",&a[i]);ll z=0,mark1=0,mark2=0,ans=1e18;for(ll i=1;i<k;i++)Insert(rt,a[i],1),z+=a[i];for(ll i=k;i<=n;i++){Insert(rt,a[i],1);z+=a[i];ll S=0,val=GetVal(rt,k-k/2,S);S=(z-S)-k/2*val+(k-k/2)*val-S;if(ans>S)ans=S,mark1=i,mark2=val;Insert(rt,a[i-k+1],-1);z-=a[i-k+1];}printf("%lld\n",ans);for(ll i=1;i<=n;i++){if(i>mark1-k&&i<=mark1)printf("%lld\n",mark2);else printf("%lld\n",a[i]);}return 0;
}