Climbing Stairs

LeetCode https://leetcode.cn/problems/climbing-stairs/

class Solution {
    public int climbStairs(int n) {
        
        if (n < 3) return n;

        int[] memo = new int[n];
        memo[0] = 1;
        memo[1] = 2;
        for (int i = 2; i < n; ++i) {
            memo[i] = memo[i - 1] + memo[i - 2];
        }

        return memo[n - 1];
    }
}

Complexity

• Time = O(n)
• Space = O(1)

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