minCostClimbingStairs = (cost) => {
    let [ downOne, downTwo ] = [ 0, 0 ];

    for (let i = 2; i < cost.length + 1; i++) {/* Time O(N) */
        const temp = downOne;

        const [ _prev, _prevPrev ] = [ (i - 1), (i - 2) ];
        const prev = downOne + cost[_prev];
        const prevPrev = downTwo + cost[_prevPrev];

        downOne = Math.min(prev, prevPrev);
        downTwo = temp;
    }

    return downOne;
}
DP - Bottom Up
Time O(N) | Space O(1)
https://leetcode.com/problems/min-cost-climbing-stairs/
@param {number[]} cost
@return {number}