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