Min Cost climbing stairs(DP | Bottom-up )

min_cost_climbing_stairs.java

class Solution {
    public int minCostClimbingStairs(int[] cost) {
        // The array's length should be 1 longer than the length of cost
        // This is because we can treat the "top floor" as a step to reach
        int minimumCost[] = new int[cost.length + 1];
        
        // Start iteration from step 2, since the minimum cost of reaching
        // step 0 and step 1 is 0
        for (int i = 2; i < minimumCost.length; i++) {
            int takeOneStep = minimumCost[i - 1] + cost[i - 1];
            int takeTwoSteps = minimumCost[i - 2] + cost[i - 2];
            minimumCost[i] = Math.min(takeOneStep, takeTwoSteps);
        }
        
        // The final element in minimumCost refers to the top floor
        return minimumCost[minimumCost.length - 1];
    }
}