【线段树】 HDOJ 4967 Handling the Past

比较绕的题目，线段树维护栈中操作。。。

#include <iostream>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <climits>  
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 50005
#define maxm 40005
#define eps 1e-10
#define mod 998244353
#define INF 999999999
#define lowbit(x) (x&(-x))
#define mp mark_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid  
#define rson o<<1 | 1, mid+1, R
//#pragma comment (linker,"/STACK:102400000,102400000")
typedef long long LL;
//typedef int LL;
using namespace std;
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
// head

struct opr
{
	char k;
	int x, t;
}op[maxn];
int sum[maxn<<2], rmax[maxn<<2];
int tt[maxn], tx[maxn];
int tcnt, n, m, p, v, ql, qr, ans, limit;
char ss[maxn];

void scanf(char *s)
{
	char ch = getchar();
	while(ch != 'p') ch = getchar();
	ss[0] = ch, ss[1] = getchar(), getchar(), getchar();
}
int cmp(int a, int b)
{
	return a < b;
}
int search(int x)
{
	int top = tcnt, bot = 1, mid;
	while(top >= bot) {
		mid = (top+bot)>>1;
		if(tt[mid] == x) break;
		if(tt[mid] > x) top = mid-1;
		else bot = mid+1;
	}
	return mid;
}
void init(void)
{
	memset(tx, 0, sizeof tx);
	memset(sum, 0, sizeof sum);
	memset(rmax, 0, sizeof rmax);
}
void read(void)
{
	for(int i = 1; i <= n; i++) {
		//scanf("%s", ss);
		scanf(ss);
		op[i].k = ss[1];
		if(op[i].k == 'u') scanf(op[i].x), scanf(op[i].t);//scanf("%d%d", &op[i].x, &op[i].t);
		else scanf(op[i].t);//scanf("%d", &op[i].t);
		tt[i] = op[i].t;
	}
	sort(tt+1, tt+n+1, cmp);
	tcnt = n;
	for(int i = 1; i <= n; i++) op[i].t = search(op[i].t);
}
void pushup(int o)
{
	sum[o] = sum[ls] + sum[rs];
	rmax[o] = max(rmax[rs], sum[rs] + rmax[ls]);
}
void updata(int o, int L, int R)
{
	if(L == R) {
		sum[o] = rmax[o] = v;
		return;
	}
	int mid = (L+R)>>1;
	if(p <= mid) updata(lson);
	else updata(rson);
	pushup(o);
}
void query(int o, int L, int R)
{
	if(ans) return;
	int mid = (L+R)>>1;
	if(L == R) {
		limit += sum[o];
		if(limit > 0) ans = L;
		return;
	}
	if(ql <= L && qr >= R) {
		if(limit + rmax[o] > 0) {
			if(limit + rmax[rs] > 0) query(rson);
			else limit += sum[rs], query(lson);
		}
		else limit += sum[o];
		return;
	}
	if(qr > mid) query(rson);
	if(ql <= mid) query(lson);
}
void work(void)
{
	for(int i = 1; i <= n; i++) {
		if(op[i].k == 'u') p = op[i].t, v = 1, tx[op[i].t] = op[i].x, updata(1, 1, tcnt);
		if(op[i].k == 'o') p = op[i].t, v = -1, updata(1, 1, tcnt);
		if(op[i].k == 'e') {
			ans = limit = 0;
			ql = 1, qr = op[i].t-1;
			query(1, 1, tcnt);
			if(ans) printf("%d\n", tx[ans]);
			else printf("-1\n");
		}
	}
}
int main(void)
{
	int _ = 0;
	while(scanf("%d", &n), n != 0) {
		init();
		read();
		printf("Case #%d:\n", ++_);
		work();
	}
	return 0;
}