You are climbing a stair case. It takes *n* steps to reach to the top.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

public int climbStairs(int n) { if (n <= 1) { return n; } int[] result = new int[n + 1]; result[0] = 1; result[1] = 1; for (int i = 2; i <= n; i++) { result[i] = result[i - 1] + result[i - 2]; } return result[n]; }

O(N)