[ZJOI2010]基站选址（线段树优化dp）

Posted 2021-02-01 owencodeisking

坑待填。

(Code Below:)

#include <bits/stdc++.h>
#define lson (rt<<1)
#define rson (rt<<1|1)
using namespace std;
const int maxn=20000+10;
const int inf=0x3f3f3f3f;
int n,k,d[maxn],c[maxn],s[maxn],w[maxn],f[maxn],st[maxn],ed[maxn],sum[maxn<<2],lazy[maxn<<2];
vector<int> q[maxn];

inline int read(){
    register int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
    while(isdigit(ch)){x=(x<<3)+(x<<1)+ch-'0';ch=getchar();}
    return (f==1)?x:-x;
}

inline void pushup(int rt){
    sum[rt]=min(sum[lson],sum[rson]);
}

inline void pushdown(int rt){
    if(lazy[rt]){
        sum[lson]+=lazy[rt];sum[rson]+=lazy[rt];
        lazy[lson]+=lazy[rt];lazy[rson]+=lazy[rt];
        lazy[rt]=0;
    }
}

void build(int l,int r,int rt){
    lazy[rt]=0;
    if(l == r){
        sum[rt]=f[l];
        return ;
    }
    int mid=(l+r)>>1;
    build(l,mid,lson);
    build(mid+1,r,rson);
    pushup(rt);
}

void update(int L,int R,int C,int l,int r,int rt){
    if(L <= l && r <= R){
        sum[rt]+=C;lazy[rt]+=C;
        return ;
    }
    pushdown(rt);
    int mid=(l+r)>>1;
    if(L <= mid) update(L,R,C,l,mid,lson);
    if(R > mid) update(L,R,C,mid+1,r,rson);
    pushup(rt);
}

int query(int L,int R,int l,int r,int rt){
    if(L > R) return 0;
    if(L <= l && r <= R){
        return sum[rt];
    }
    pushdown(rt);
    int mid=(l+r)>>1,ans=inf;
    if(L <= mid) ans=min(ans,query(L,R,l,mid,lson));
    if(R > mid) ans=min(ans,query(L,R,mid+1,r,rson));
    return ans;
}

int main()
{
    n=read(),k=read();
    for(int i=2;i<=n;i++) d[i]=read();
    for(int i=1;i<=n;i++) c[i]=read();
    for(int i=1;i<=n;i++) s[i]=read();
    for(int i=1;i<=n;i++) w[i]=read();
    d[++n]=inf;w[n]=inf;k++;
    for(int i=1;i<=n;i++){
        st[i]=lower_bound(d+1,d+n+1,d[i]-s[i])-d;
        ed[i]=lower_bound(d+1,d+n+1,d[i]+s[i])-d;
        if(d[ed[i]]>d[i]+s[i]) ed[i]--;
        q[ed[i]].push_back(i);
    }
    int x,ans,val=0;
    for(int i=1;i<=n;i++){
        f[i]=val+c[i];
        for(int j=0;j<q[i].size();j++){
            x=q[i][j];val+=w[x];
        }
    }
    ans=f[n];
    for(int t=2;t<=k;t++){
        build(1,n,1);
        for(int i=1;i<=n;i++){
            f[i]=query(1,i-1,1,n,1)+c[i];
            for(int j=0;j<q[i].size();j++){
                x=q[i][j];
                if(st[x]>1) update(1,st[x]-1,w[x],1,n,1);
            }
        }
        ans=min(ans,f[n]);
    }
    printf("%d
",ans);
    return 0;
}