SOURCE

function findMaxLength(nums){
    const map = new Map();
    map.set(0,-1);
    let maxLength = 0;
    let count = 0;

    for(let i =0;i<nums.length;i++){
        count += nums[i] === 1 ?1:-1;
        if(map.has(count)){
            maxLength = Math.max(maxLength,i-map.get(count))
        } else {
            map.set(count,i)
        }
    }
    return maxLength
}

const arr =[0,0,0,1,1,0,1,0,0];
const result = findMaxLength(arr)
console.log(result)