$$\color{Red}{最长连续不重复子序列-【双指针】（三种语言）}$$

这里附带打个广告——————我做的所有的题解

包括基础提高以及一些零散刷的各种各样的题

java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    static int n, N = 100010;
    static int[] cnt = new int[N];
    static int[] a = new int[N];
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws IOException {
        n = Integer.parseInt(br.readLine());
        String [] s = br.readLine().split(" ");
        int res = 0;
        for (int i = 0, j = 0; j < n; j++) {
            a[j] = Integer.parseInt(s[j]);
            cnt[a[j]] += 1;
            while(cnt[a[j]] > 1) cnt[a[i++]] -= 1;
            res = Math.max(res, j - i + 1);
        }
        System.out.println(res);
    }
}

python3

n = int(input())
arr = [int(x) for x in input().split()]
j, ans = 0, 0
d = {}
for i in range(n):
    if d.get(arr[i],False):
        d[arr[i]] += 1
        while d[arr[i]] > 1 and j <= i:
            d[arr[j]] -= 1
            j += 1
    else:
        d[arr[i]] = 1

    ans = max(ans, i - j + 1)
print(ans)

C++

#include <iostream>
using namespace std;

const int N = 1e5 + 10;
int a[N], b[N];

int main()
{
    int n;
    scanf("%d", &n);
    int res = 0;
    for(int i=0, j=0; i<n; i++)
    {
        cin >> a[i];
        b[a[i]] ++;
        while(b[a[i]] > 1)   b[a[j++]] --;
        //每更新一个a[i]都会计数！！这是精髓
        res = max(res, i - j + 1);
    }
    cout << res;

    return 0;
}