1101. Quick Sort (25)

1.题面

https://www.patest.cn/contests/pat-a-practise/1101

2.题意

找轴点

3.思路

维护两个数组记录结果，没什么意思，值得吐槽的是就算不存在轴点，也要求输出一个空行

4.代码

/*****************************************************************
    > File Name: cpp_acm.cpp
    > Author: Uncle_Sugar
    > Mail: [email protected]
    > Created Time: Thu 02 Feb 2017 16:19:56 CST
*****************************************************************/
# include <cstdio>
# include <cstring>
# include <cctype>
# include <cmath>
# include <cstdlib>
# include <climits>
# include <iostream>
# include <iomanip>
# include <set>
# include <map>
# include <vector>
# include <stack>
# include <queue>
# include <algorithm>
using namespace std;

# define rep(i,a,b) for (i=a;i<=b;i++)
# define rrep(i,a,b) for (i=b;i>=a;i--)
# define mset(aim, val) memset(aim, val, sizeof(aim))

struct QuickIO{
	QuickIO(){const int SZ = 1<<20;
		setvbuf(stdin ,new char[SZ],_IOFBF,SZ);
		setvbuf(stdout,new char[SZ],_IOFBF,SZ);
	}				//*From programcaicai*//
}QIO;

template<class T>void PrintArray(T* first,T* last,char delim=' '){
    for (;first!=last;first++) cout << *first << (first+1==last?'\n':delim);
}

/*
1.see the size of the input data before you select your algorithm 
2.cin&cout is not recommended in ACM/ICPC
3.pay attention to the size you defined, for instance the size of edge is double the size of vertex
*/

const int debug = 1;
const int size  = 10 + 100000; 
const int INF = INT_MAX>>1;
typedef long long ll;

int a[size], al[size], ar[size];

int main(){
	std::ios::sync_with_stdio(false);cin.tie(0);
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++){
		cin >> a[i];
	}
	a[0] = -INF;
	a[n+1] = INF;
	al[0] = a[0];
	for (int i = 1; i <= n; i++){
		al[i] = max(al[i-1], a[i]);
	}
	ar[n+1] = a[n+1];
	for (int i = n; i >= 1; i--){
		ar[i] = min(ar[i+1], a[i]);
	}
	int cnt = 0;
	vector<int> vct;
	for (int i = 1; i <= n; i++){
		if (a[i] >= al[i-1] && a[i] <= ar[i+1]){
			cnt++; vct.push_back(a[i]);
		}
	}
	cout << cnt << endl;
	if (!cnt) puts("");
	for (int i = 0; i < vct.size(); i++){
		cout << vct[i] << (i==vct.size()-1?'\n':' ');
	}
	return 0;
}