MinCostClimbingStairs.java

// On a staircase, the i-th step has some non-negative cost cost[i] assigned (0 indexed).
// Once you pay the cost, you can either climb one or two steps. You need to find minimum 
// cost to reach the top of the floor, and you can either start from the step with index 0, 
// or the step with index 1.
// See: https://leetcode.com/problems/min-cost-climbing-stairs/
// See: https://leetcode.com/problems/min-cost-climbing-stairs/discuss/599901/Java-2-lines-DP

package leetcode.dynamic_programming;

public class MinCostClimbingStairs {

    public int minCostClimbingStairs(int[] cost) {
        for (int i = 2; i < cost.length; i++)
            cost[i] += Math.min(cost[i - 1], cost[i - 2]);
        return Math.min(cost[cost.length - 1], cost[cost.length - 2]);
    }

    public static void main(String[] args) {
        MinCostClimbingStairs sln = new MinCostClimbingStairs();

        System.out.println(sln.minCostClimbingStairs(new int[] { 10, 15, 20 }));
        System.out.println(
                sln.minCostClimbingStairs(new int[] { 1, 100, 1, 1, 1, 100, 1, 1, 100, 1 }));
    }

}