week 2: climbing stairs

Author: prograsshopper

climbing-stairs/prograsshopper.py

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+class Solution:
+    def climbStairs(self, n: int) -> int:
+        '''
+        sol 1
+        Runtime: Beats 100.00% / O(n^2)
+        Memory: Beats 8.16% / O(1)
+        '''
+        import math
+        ways = 1
+        max_count_2steps = int(n/2)
+        for i in range(1, max_count_2steps+1):
+            current = math.perm(n - i) / (math.perm(i) * math.perm(n-(2*i)))
+            ways += current
+        return int(ways)
+
+        '''
+        sol 2
+        Runtime: Beats 100.00% / O(n^2)
+        Memory: Beats 48.54% / O(1)
+        '''
+        ways = 0
+        max_count_2steps = n // 2
+        for i in range(max_count_2steps + 1):
+            ways += math.comb(n - i, i)
+        return ways