题目描述

https://www.acwing.com/problem/content/description/801/

C++ 代码

#include<iostream>
#include<cstdio>
using namespace std;
int a[100010],s[100010],n;
int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
        scanf("%d",&a[i]);
    int res=0;
    for(int i=1,j=1;i<=n;i++)
    {
        s[a[i]]++;
        while(s[a[i]]>1)
        {
            s[a[j]]--;
            j++;
        }
        res=max(res,i-j+1);
    }
    cout<<res;
    return 0;
}