模拟赛 yjqa

#include<bits/stdc++.h>
#define reg register int
#define il inline
#define mid ((l+r)>>1)
#define numb (ch^‘0‘)
#define ls (x<<1)
#define rs (x<<1|1)
using namespace std;
typedef long long ll;
il void rd(int &x){
    char ch;x=0;bool fl=false;
    while(!isdigit(ch=getchar()))(ch==‘-‘)&&(fl=true);
    for(x=numb;isdigit(ch=getchar());x=x*10+numb);
    (fl==true)&&(x=-x);
}
namespace Miracle{
const int N=100000+5;
int n;
struct node{
    ll mi,fmi,vmi,fmx;
    ll ch;
    node(){
        ch=-1;
    }
}t[8*N];
int tim[N],a[N];
int b[N];
int sta[2*N],top;
ll f[N];
void pushup(int x){
    t[x].mi=min(t[x<<1].mi,t[x<<1|1].mi);
    t[x].fmi=min(t[x<<1].fmi,t[x<<1|1].fmi);
    t[x].vmi=min(t[x<<1].vmi,t[x<<1|1].vmi);
    t[x].fmx=max(t[ls].fmx,t[rs].fmx);
}
void pushdown(int x){
    if(t[x].ch==-1) return;
    t[ls].ch=t[x].ch;
    t[ls].vmi=t[x].ch;
    t[ls].mi=t[ls].fmi+2*t[ls].vmi;
    
    t[rs].ch=t[x].ch;
    t[rs].vmi=t[x].ch;
    t[rs].mi=t[rs].fmi+2*t[rs].vmi;
    t[x].ch=-1;
}
void upda(int x,int l,int r,int to,ll ak,ll c){
    if(l==r){
        t[x].fmi=c;
        t[x].fmx=c;
        t[x].vmi=ak;
        t[x].mi=t[x].fmi+2*t[x].vmi;
        return;
    }
    pushdown(x);
    if(to<=mid) upda(x<<1,l,mid,to,ak,c);
    else upda(x<<1|1,mid+1,r,to,ak,c);
    pushup(x);
}
void chan(int x,int l,int r,int L,int R,ll c){
    if(L<=l&&r<=R){
        t[x].ch=c;
        t[x].vmi=t[x].ch;
        t[x].mi=t[x].fmi+2*t[x].vmi;
        return;
    }
    pushdown(x);
    if(L<=mid) chan(x<<1,l,mid,L,R,c);
    if(mid<R) chan(x<<1|1,mid+1,r,L,R,c);
    pushup(x);
}
ll query(int x,int l,int r,int L,int R,ll c){
    if(L<=l&&r<=R){
        pushdown(x);
        if(t[x].fmi<t[x].fmx&&t[x].fmi<=c&&c<=t[x].fmx){
            return min(query(x<<1,l,mid,L,R,c),query(x<<1|1,mid+1,r,L,R,c));
        }
        if(t[x].fmx<=c){
            return c+2*t[x].vmi;
        }
        if(t[x].fmi>=c){
            return t[x].mi;
        }
    }
    pushdown(x);
    ll ret=0x3f3f3f3f3f3f3f3f;
    if(L<=mid) ret=min(ret,query(x<<1,l,mid,L,R,c));
    if(mid<R) ret=min(ret,query(x<<1|1,mid+1,r,L,R,c));
    return ret;
}
int main(){
    rd(n);
    for(reg i=2;i<=n+1;++i){
        rd(tim[i]),rd(a[i]);
    }
    for(reg i=1;i<=n;++i){
        b[i]=a[i+1];
    }
    sta[++top]=1;
    upda(1,1,n,1,b[1],0);
    for(reg i=2;i<=n+1;++i){
        //cout<<" ii "<<i<<endl;
        
        
        f[i]=query(1,1,n,1,i-1,tim[i]);
        //cout<<" f[i] "<<f[i]<<endl;
        if(i!=n+1)
        {
        upda(1,1,n,i,b[i],f[i]);
        while(top&&b[sta[top]]<b[i]){
            //cout<<sta[top]<<endl;
            chan(1,1,n,sta[top-1]+1,sta[top],b[i]);
            --top;
        }
        sta[++top]=i;
        }
    }
    printf("%lld",f[n+1]);
    return 0;
}

}
signed main(){
    Miracle::main();
    return 0;
}

/*
   Author: *Miracle*
   Date: 2018/12/24 21:59:28
*/