codeforces 374D. Inna and Sequence 线段树

#include <iostream>
#include <vector>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <string>
#include <queue>
#include <stack>
#include <bitset>
using namespace std;
#define pb(x) push_back(x)
#define ll long long
#define mk(x, y) make_pair(x, y)
#define lson l, m, rt<<1
#define mem(a) memset(a, 0, sizeof(a))
#define rson m+1, r, rt<<1|1
#define mem1(a) memset(a, -1, sizeof(a))
#define mem2(a) memset(a, 0x3f, sizeof(a))
#define rep(i, n, a) for(int i = a; i<n; i++)
#define fi first
#define se second
typedef pair<int, int> pll;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int mod = 1e9+7;
const int inf = 1061109567;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
const int maxn = 1e6+5;
int sum[maxn<<2], val[maxn], a[maxn], now = 1;
void pushUp(int rt) {
    sum[rt] = sum[rt<<1]+sum[rt<<1|1];
}
void update(int p, int x, int l, int r, int rt) {
    if(l == r) {
        sum[rt] = 1;
        val[l] = x;
        return ;
    }
    int m = l+r>>1;
    if(p<=m)
        update(p, x, lson);
    else
        update(p, x, rson);
    pushUp(rt);
}
void remove(int p, int l, int r, int rt) {
    if(l == r) {
        sum[rt] = 0;
        return ;
    }
    int m = l+r>>1;
    if(sum[rt<<1]>=p) {
        remove(p, lson);
    } else {
        remove(p-sum[rt<<1], rson);
    }
    pushUp(rt);
}
void output(int l, int r, int rt) {
    if(l == r) {
        printf("%d", val[l]);
        return ;
    }
    int m = l+r>>1;
    if(sum[rt<<1])
        output(lson);
    if(sum[rt<<1|1])
        output(rson);
}
int main()
{
    int n, m, sign;
    scanf("%d%d", &n, &m);
    for(int i = 0; i<m; i++) {
        scanf("%d", &a[i]);
    }
    for(int j = 0; j<n; j++) {
        scanf("%d", &sign);
        if(sign>=0) {
            update(now++, sign, 1, n+2, 1);
        } else {
            for(int i = 0; i<m; i++) {
                if(a[i]-i>sum[1])           //这里注意是a[i]-i, 因为之前已经删了i个数
                    break;
                remove(a[i]-i, 1, n+2, 1);
            }
        }
    }
    if(sum[1]) {
        output(1, n+2, 1);
    } else {
        puts("Poor stack!");
    }
    return 0;
}