PAT甲1101 Quick Sort

题意

在快速排序中，给定一串经过一次划分的数字，找出可能的pivot

源码

#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
int n;
int a[1000005]; 
int mark[1000005];
bool cmp(int x,int y){
	return x<y;
} 
const int maxInt=1e9+5;
int main(){
	memset(mark,0,sizeof(mark));
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	a[0]=-1;
	a[n+1]=maxInt;
	
	int curmin=a[n+1];
	int curmax=a[0];
	for(int i=1;i<=n;i++){
		if(curmax<a[i]){
			mark[i]++;
			curmax=a[i];
		}
	}
	for(int i=n;i>=1;i--){
		if(curmin>a[i]){
			mark[i]++;
			curmin=a[i];
		}
	}
	int counter=0;
	vector<int>res;
	for(int i=1;i<=n;i++){
		if(mark[i]==2){
			counter++;
			res.push_back(a[i]);
		}
	}
	cout<<counter<<endl;
	if(counter==0){
		cout<<""<<endl;
		return 0;
	}
	sort(res.begin(),res.end(),cmp);
	int len=res.size();
	for(int i=0;i<len-1;i++){
		cout<<res[i]<<" ";
	}
	cout<<res[res.size()-1]<<endl;
	return 0;
	
}