class Solution {
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]);
}
}
Time: O(n) Space: O(1)