Problem Statement

Practice Here


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? Note: Given n will be a positive integer.


Example

Input: 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps

Solution

 	class Solution {
    public int climbStairs(int n) {
        if (n < 3) return n;
        int[] arr = new int[n+1];
        arr[1] = 1;
        arr[2] = 2;
        for (int i = 3; i<= n; i++) {
            arr[i] = arr[i-1] + arr[i-2];
        }
        return arr[n];        
    }
}

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