Finding the largest subarray with equal number of 0's and 1's

Question

So, I have an array containing only 0\'s and 1\'s. I have to find out the largest subarray containing equal number of 0\'s and 1\'s. One can be a naive approach have complex

Answer 1

JS implementation of the @templatetypedef algorithm with a modification of using a map to help find the max length

function findMaxLen(a) {
// secondary array, initialized with the first element as 0
let b = [0]
let sum = 0

// populate the secondary array and update the sum as per the algorithm
for (let i = 0; i < a.length; i++) {
    b[i + 1] = a[i] == 0 ? sum - 1 : sum + 1
    sum = b[i + 1]
}

// map of sum vs the first index of the secondary array with the sum value
let map = new Map()
let maxLen = 0

for (let i = 0; i < b.length; i++) {
    if (map.has(b[i]))
        maxLen = Math.max(maxLen, i - map.get(b[i]))
    else
        map.set(b[i], i)
}

return maxLen
}