LeetCode in Kotlin

525. Contiguous Array

Medium

Given a binary array nums, return the maximum length of a contiguous subarray with an equal number of 0 and 1.

Example 1:

Input: nums = [0,1]

Output: 2

Explanation: [0, 1] is the longest contiguous subarray with an equal number of 0 and 1.

Example 2:

Input: nums = [0,1,0]

Output: 2

Explanation: [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.

Constraints:

• 1 <= nums.length <= 105
• nums[i] is either 0 or 1.

Solution

class Solution {
    fun findMaxLength(nums: IntArray): Int {
        for (i in nums.indices) {
            if (nums[i] == 0) {
                nums[i] = -1
            }
        }
        val map: HashMap<Int, Int> = HashMap()
        map[0] = -1
        var ps = 0
        var len = 0
        for (i in nums.indices) {
            ps += nums[i]
            if (!map.containsKey(ps)) {
                map[ps] = i
            } else {
                len = Math.max(len, i - map[ps]!!)
            }
        }
        return len
    }
}

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