Codeforces Round #220 (Div. 2) D - Inna and Sequence

D - Inna and Sequence

线段数维护区间有几个没有被删除的数，利用线段树的二分找第几个数在哪里，然后模拟更新就好啦。

#include<bits/stdc++.h>
#define fi first
#define se second
#define mk make_pair
#define pii make_pair
#define ll long long
#define read(x) scanf("%d",&x)
#define sread(x) scanf("%s",x)
#define dread(x) scanf("%lf",&x)
#define lread(x) scanf("%lld",&x)
using namespace std;
const int inf=0x3f3f3f3f;
const int N=2e6+;
int n,m,a[N],dfn;
struct seg_tree
{
    struct node
    {
        int l,r,sum,v;
    }a[N<<];
    void Build(int l,int r,int rt)
    {
        a[rt].l=l; a[rt].r=r;
        a[rt].sum=a[rt].v=;
        if(l==r) return;
        int mid=(l+r)>>;
        Build(l,mid,rt<<);
        Build(mid+,r,rt<<|);
    }
    void Modify(int pos,int rt,int v)
    {
        int l=a[rt].l,r=a[rt].r;
        if(l==r && l==pos)
        {
            a[rt].v=v;
            a[rt].sum=;
            return;
        }
        int mid=(l+r)>>;
        if(pos<=mid) Modify(pos,rt<<,v);
        else Modify(pos,rt<<|,v);
        a[rt].sum=a[rt<<].sum+a[rt<<|].sum;
    }
    void Delete(int pos,int rt)
    {
        int l=a[rt].l, r=a[rt].r;
        if(l==r)
        {
            a[rt].sum=;
            a[rt].v=;
            return;
        }
        if(pos<=a[rt<<].sum)
            Delete(pos,rt<<);
        else
            Delete(pos-a[rt<<].sum,rt<<|);
        a[rt].sum=a[rt<<].sum+a[rt<<|].sum;
    }
    void Print(int rt)
    {
        int l=a[rt].l,r=a[rt].r;
        if(l==r)
        {
            printf("%d",a[rt].v);
            return;
        }
        if(a[rt<<].sum)
            Print(rt<<);
        if(a[rt<<|].sum)
            Print(rt<<|);
    }
}seg;
int main()
{
    read(n),read(m);
    for(int i=;i<m;i++)
        read(a[i]);
    seg.Build(,n+,);
    while(n--)
    {
        int op; read(op);
        if(op==-)
        {
            for(int i=;i<m;i++)
            {
                if(seg.a[].sum<a[i]-i)
                    break;
                seg.Delete(a[i]-i,);
            }
        }
        else seg.Modify(++dfn,,op);
    }
    if(!seg.a[].sum)
        puts("Poor stack!");
    else
        seg.Print();
    return ;
}