Number of Visible People in a Queue.js

// Runtime: 354 ms (Top 65.08%) | Memory: 83 MB (Top 6.35%)
var visibleToRight = function(heights){
    const result = new Array(heights.length).fill(0)
    const stack = []

    let i = heights.length-1

    // loop from right to left
    while(i >= 0){
        let popCount = 0

        // Keep Popping untill top ele is smaller
        while(stack.length > 0 && stack[stack.length-1][0] < heights[i]){
            stack.pop()
            popCount+=1
        }

        /////////////////////
        /// After Popping ///
        ////////////////////

        // Case1: if ALL elements got popped
        if(stack.length === 0)
            result[i] = popCount // mark

        // Case2: if NO elements were popped
        else if(popCount === 0)
            result[i] = 1 // mark

        // Case3: if SOME elements were popped
        else
            result[i] = popCount+1 // mark

        // store
        stack.push([heights[i],popCount])

        i-=1
    }

    return result
}
var canSeePersonsCount = function(heights) {
    return visibleToRight(heights)
};