2419. Longest Subarray With Maximum Bitwise AND

Medium

You are given an integer array nums of size n.

Consider a non-empty subarray from nums that has the maximum possible bitwise AND.

• In other words, let k be the maximum value of the bitwise AND of any subarray of nums. Then, only subarrays with a bitwise AND equal to k should be considered.

Return the length of the longest such subarray.

The bitwise AND of an array is the bitwise AND of all the numbers in it.

A subarray is a contiguous sequence of elements within an array.

Example 1:

Input: nums = [1,2,3,3,2,2]
Output: 2
Explanation:
The maximum possible bitwise AND of a subarray is 3.
The longest subarray with that value is [3,3], so we return 2.

Example 2:

Input: nums = [1,2,3,4]
Output: 1
Explanation:
The maximum possible bitwise AND of a subarray is 4.
The longest subarray with that value is [4], so we return 1.

Constraints:

• 1 <= nums.length <= 10^5

• 1 <= nums[i] <= 10^6

解題

最大的數字和自己以外的數字做AND就會變小，所以答案其實就是陣列內最大的值它的最大subarray。

Runtime: 124 ms, faster than 100%

Memory Usage: 9.6 MB, less than 33.33%

func longestSubarray(nums []int) int {
    maxv := math.MinInt32
    count := 0
    ans := 0

    for _, v := range nums {
        if v > maxv { maxv = v }
    }

    for _, v := range nums {
        if v == maxv { 
            count++
            if count > ans { ans = count }
        } else {
            count = 0
        }
    }

    return ans
}