Contiguous Array

Description

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

Example 1:

Input: [0,1]
Output: 2
Explanation: [0, 1] is the longest contiguous subarray with equal number of 0 and 1.

Example 2:

Input: [0,1,0]
Output: 2
Explanation: [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.

Note: The length of the given binary array will not exceed 50,000.

Solution(javascript)

/**
 * @param {number[]} nums
 * @return {number}
 */
var findMaxLength = function(nums) {
    const map = {
        0: -1
    }
    let sum = 0
    let max = 0
    for(let i = 0; i < nums.length; i++){
        sum += nums[i] === 0 ? -1 : 1 
        
        if(map[sum] !== undefined) {
            max =Math.max(max, i-map[sum])
        } else {
            map[sum] = i
        }
    }
    return max
};