CodeForces 374D Inna and Sequence

#include<bits/stdc++.h>
using namespace std;
#define for(i,a,b) for(int i=a;i<=b;++i)

const int maxn=1e6+5;
int w[maxn];
int ftree[maxn];
int a[maxn];
int tmp[maxn];
int n,m;

int lowbit(int x)
{
	return x&(-x);
}
int sum(int i)
{
	int s=0;
	while(i>0)
	{
		s+=ftree[i];
		i-=lowbit(i);
	}
	return s;
}
void add(int i,int x)
{
	while(i<=n)
	{
		ftree[i]+=x;
		i+=lowbit(i);
	}
}
int ask(int i)
{
	return sum(i)-sum(i-1);
}
int lookfor(int x,int n)
{
	if(x>sum(n))return -1;
	int l,m,r;
	l=1,r=n;
	while(l<r)
	{
		m=(l+r)/2;
		if(sum(m)<x)l=m+1;
		else r=m;
	}
	return l;
}
int main()
{
	while(~scanf("%d%d",&n,&m))//each case
	{
		memset(ftree,0,sizeof ftree);
		for(i,1,m)scanf("%d",a+i);
		int op;
		int now=0;
		for(i,1,n)//i of n operation
		{
			scanf("%d",&op);
			if(op<0)
			{
				vector<int> tmp;
				for(j,1,m)//j of m deleting array
				{
					int kk=lookfor(a[j],now);
					if(kk<0)break;
					else tmp.push_back(kk);
				}
				int kk=tmp.size();
				for(i,0,kk-1)add(tmp[i],-1);
			}
			else
			{
				w[++now]=op;
				add(now,1);
			}
		}
		int flag=0;
		for(i,1,now)
			if(ask(i)==1)
			{
				flag=1;
				printf("%d",w[i]);
			}
		if(flag==0)printf("Poor stack!");
		printf("
");
	}
}