chore: clean up content phase organization

work/1/Easy/Math/70.climbing-stairs.py

@@ -0,0 +1,53 @@
+"""
+70. Climbing Stairs
+Difficulty: Easy
+https://leetcode.com/problems/climbing-stairs/
+
+──────────────────────────────────────────────────
+
+You are climbing a staircase. It takes n steps to reach the top.
+
+Each time you can either climb 1 or 2 steps. In how many distinct
+ways can you climb to the top?
+
+
+
+Example 1:
+
+Input: n = 2
+Output: 2
+Explanation: There are two ways to climb to the top.
+1. 1 step + 1 step
+2. 2 steps
+
+Example 2:
+
+Input: n = 3
+Output: 3
+Explanation: There are three ways to climb to the top.
+1. 1 step + 1 step + 1 step
+2. 1 step + 2 steps
+3. 2 steps + 1 step
+
+
+
+Constraints:
+
+        • 1 <= n <= 45
+"""
+
+
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        if n == 1:
+            return 1
+        if n == 2:
+            return 2
+
+        first, second = 1, 2
+
+        for _ in range(3, n + 1):
+            third = first + second
+            first, second = second, third
+
+        return second