treemap/treeset 相关 1438

1438. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit Medium 2790115Add to ListShare

Given an array of integers nums and an integer limit, return the size of the longest non-empty subarray such that the absolute difference between any two elements of this subarray is less than or equal to limit.

 Example 1:

Input: nums = [8,2,4,7], limit = 4
Output: 2 
Explanation: All subarrays are: 
[8] with maximum absolute diff |8-8| = 0 <= 4.
[8,2] with maximum absolute diff |8-2| = 6 > 4. 
[8,2,4] with maximum absolute diff |8-2| = 6 > 4.
[8,2,4,7] with maximum absolute diff |8-2| = 6 > 4.
[2] with maximum absolute diff |2-2| = 0 <= 4.
[2,4] with maximum absolute diff |2-4| = 2 <= 4.
[2,4,7] with maximum absolute diff |2-7| = 5 > 4.
[4] with maximum absolute diff |4-4| = 0 <= 4.
[4,7] with maximum absolute diff |4-7| = 3 <= 4.
[7] with maximum absolute diff |7-7| = 0 <= 4. 
Therefore, the size of the longest subarray is 2.

Example 2:

Input: nums = [10,1,2,4,7,2], limit = 5
Output: 4 
Explanation: The subarray [2,4,7,2] is the longest since the maximum absolute diff is |2-7| = 5 <= 5.

Example 3:

Input: nums = [4,2,2,2,4,4,2,2], limit = 0
Output: 3

 Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 109
• 0 <= limit <= 109


class Solution {
    public int longestSubarray(int[] nums, int limit) {
        TreeSet<Integer> tree = new TreeSet<Integer>((x,y)->{
            return nums[x]==nums[y] ? x-y : nums[x]-nums[y];
        });
        int left = 0;
        int result = 0;
        for(int i=0; i < nums.length; i++){
            tree.add(i);
            while(nums[tree.last()]-nums[tree.first()]>limit){
                tree.remove(left++);
            }
            result = Math.max(result, i-left+1);
        }
        return result;
    }
}