题目链接：点击打开链接
给定n个操作，m长的序列a
下面n个数
if(co>=0)则向字符串添加一个co （开始是空字符串）
else 删除字符串中有a的下标的字符
直接在序列上搞，简单模拟
#include<stdio.h>
#include<iostream>
#include<string.h>
#include<set>
#include<vector>
#include<map>
#include<math.h>
#include<string>
#include<stdlib.h>
#include<algorithm>
using namespace std;
#define N 1000005
bool use[N], b[N];
int top;
int n, m;
int a[N];
int c[N], maxn;
inline int lowbit(int x){return x&(-x);}
void change(int pos, int val){
while(pos<=maxn){
c[pos]+=val;
pos+=lowbit(pos);
}
}
int sum(int pos){
int ans = 0;
while(pos)ans+=c[pos], pos-=lowbit(pos);
return ans;
}
set<int>myset;
set<int>::iterator p;
void Erase(int pos, int r){
int l = 1;
while(l<=r) {
int mid = (l+r)>>1;
int tmp = sum(mid);
if(tmp==pos) {
p = myset.upper_bound(mid);
p--;
mid = *p;
change(mid, -1);
use[mid] = 1;
myset.erase(p);
return ;
}
if(tmp>pos) r = mid-1;
else l = mid+1;
}
}
void init(){myset.clear(); memset(c, 0, sizeof c); maxn = n+10; top = 0;}
int main(){
int i,j,co;
while(~scanf("%d %d",&n,&m)){
init();
for(i=0;i<m;i++)scanf("%d",&a[i]);
int len = 0;
for(i = 1; i <= n; i++) {
scanf("%d",&co);
if(co>=0)
use[i] = 0, b[i] = co, change(i,1), len++, myset.insert(i);
else {
use[i] = 1;
int j = lower_bound(a, a+m, len) - a;
if(j==0 && len<a[0])continue;
if(len!=a[j])j--;
while(j>=0) {
Erase(a[j], i);
j--;
len--;
}
}
}
if(!len)puts("Poor stack!");
else {
for(i = 1; i <= n; i++) if(!use[i])
printf("%d",b[i]);
puts("");
}
}
return 0;
}Codeforces 374D Inna and Sequence 二分+树状数组,布布扣,bubuko.com
Codeforces 374D Inna and Sequence 二分+树状数组
原文：http://blog.csdn.net/qq574857122/article/details/34423657