799. 最长连续不重复子序列

Posted 2021-05-20 幽殇默

https://www.acwing.com/problem/content/description/801/
朴素写法:

#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;
const int N=1e5+10;
int a[N];
bool hush[N];
int ans;
int main(void)
{
	int n; cin>>n;
	for(int i=0;i<n;i++) scanf("%d",&a[i]);
	for(int i=0;i<n;i++)
	{
		int k=0;
		memset(hush,0,sizeof hush);
		for(int j=i;!hush[a[j]]&&j<n;j++)
			k++,hush[a[j]]=true;
		ans=max(ans,k);
	}
	cout<<ans<<endl;
	return 0;
}

双指针写法:

#include<cstdio>
#include<iostream>
using namespace std;
const int N=1e5+10;
int a[N],hush[N];
int n;
int ans;
int main(void)
{
	cin>>n;
	for(int i=0;i<n;i++) cin>>a[i];
	for(int i=0,j=0;i<n;i++)
	{
		hush[a[i]]++;
		while(hush[a[i]]>1)
		{
			hush[a[j]]--;
			j++;
		}
		ans=max(ans,i-j+1);
	}
	cout<<ans<<endl;
}