Water collected between towers

Question

I recently came across an interview question asked by Amazon and I am not able to find an optimized algorithm to solve this question:

You are given an input array wh

Answer 1

JavaScript Program for finding store total water:

let buildingHeights = [6, 1, 3, 5, 9, 2, 8];
/*
 * TOTAL store water
 * */
let max = (n1, n2) => {
    return n1 > n2 ? n1 : n2;
};
let min = (n1, n2) => {
    return n1 > n2 ? n2 : n1;
};

let maxHeightFromLeft = {}, maxHeightFromRight = {};
for (let i = 0; i < buildingHeights.length; i++) {
    maxHeightFromLeft[i] = max(buildingHeights[i], (i != 0) ? maxHeightFromLeft[i - 1] : 0);
}
for (let i = buildingHeights.length - 1; i >= 0; i--) {
    maxHeightFromRight[i] = max(buildingHeights[i], i < (buildingHeights.length - 1) ? maxHeightFromRight[i + 1] : 0);
}
let totalStorage = 0;
for (let i = 0; i < buildingHeights.length; i++) {
    totalStorage += min(maxHeightFromLeft[i], maxHeightFromRight[i]) - buildingHeights[i];
}
console.log(totalStorage);