Climbing Stairs

https://leetcode.com/problems/climbing-stairs/

class Solution {
public:
    int climbStairs(int n) {
        if(n==1)
            return 1;
        else if(n==2)
            return 2;
        else if(n>2)
        {
            int* nums=new int[n+1];
            nums[1]=1;
            nums[2]=2;
            for(int i=3;i<=n;i++)
            {
                nums[i]=nums[i-1]+nums[i-2];
            }
            return nums[n];
        }
        else
            return 0;
    }
};