746. Min Cost Climbing Stairs

minCostClimbingStairs.py

class Solution:
    
    def minCostClimbingStairs(self, costs: List[int]) -> int:
        
        n = len(costs)
        
        if n == 2:
            return min(costs[0], costs[1])
        
        dp = [0] * n
        
        dp[0] = costs[0]
        dp[1] = costs[1]
        
        # At every step, we can use the previous step or 2 steps 
        # to calculate the optimal cost at the current step
        
        for i in range(2, n):
            dp[i] = costs[i] + min(dp[i-1], dp[i-2])
            
        return min(dp[-1], dp[-2])