题解 | #最长无重复子数组#

package array;

import java.util.HashSet;
import java.util.Set;

/**

• @description: 无重复数字的最长子数组 滑动窗口

• @author: zhangxianglong

• @date: 2021/6/17

• @time: 19:22

• Copyright (C) 2018 Meituan

• All rights reserved

• /
  public class UNMaximalSubArray {

  public static void main(String[] args) {

    int[] arr = new int[]{1, 1, 3, 4, 2};
    int maxLength = maxLength(arr);
  
    System.out.println(maxLength(arr));

  }

  /* 滑动窗口，用set维护一个不重复的窗口 */
  public static int maxLength(int[] arr) {

    int res = 0;
    Set<Integer> set = new HashSet<Integer>();
  
    for (int l = 0, r = 0; r < arr.length; r++) {
        int a = arr[r];
        while (set.contains(a)) {
            set.remove(arr[l++]);
        }
        set.add(a);
        res = Math.max(res, r - l + 1);
    }
    return res;

  }

  /**

  • 通过滑动窗口 这种方式8/10个case能通过

  • @param nums

  • @return

  • /
    public static int maxLength2(int[] nums) {

    int left = 0;
    int right = 0;
    int max = Integer.MIN_VALUE;

    while (right < nums.length) {

      for (int i = left; i < right; i++) {
          if (nums[i] == nums[right]) {
              left++;
          }
      }
      max = Math.max(max, right - left + 1);
      right++;

    }
    return max;
    }

}