题解 | #最长无重复子数组 双指针#

import java.util.*;


public class Solution {
    /**
     * 
     * @param arr int整型一维数组 the array
     * @return int整型
     */
    public int maxLength (int[] arr) {

        if(arr == null || arr.length == 0){
            return 0;
        }
        HashMap<Integer,Integer> map = new HashMap<>();
        int left = 0;
        int right = 0;
        int ans = 0;
        while (right < arr.length){
            if (map.containsKey(arr[right])){
                left = Math.max(map.get(arr[right]) + 1, left);
            }
            map.put(arr[right],right);

            ans = Math.max(ans, right - left + 1);
            right++;
        }
        return ans;
    }
}