LeetCode 525. Contiguous Array

Question

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

https://leetcode.com/problems/contiguous-array/

• Solution1

class Solution {
    public int findMaxLength(int[] nums) {
        for (int i = 0; i < nums.length; i++) if (nums[i] == 0) nums[i] = -1;
        int res = 0, sum = 0;
        Map<Integer, Integer> map = new HashMap<>();
        map.put(0, -1);
        for (int i = 0; i < nums.length; i++){
            sum += nums[i];
            if (map.containsKey(sum)) res = Math.max(res, i - map.get(sum));
            else map.put(sum, i);
        }
        return res;
    }
}

Complexity:

Time complexity: O( n)

Space complexity: O(n)