[prograsshopper] Week 2 Solutions

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

valid-anagram/prograsshopper.py

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+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        '''
+        sol 1
+        Runtime: Beats 78.74% / O(N)
+        Memory: Beats 64.30% / O(1)
+        '''
+        s_dict = dict()
+        for elem in s:
+            try:
+                s_dict[elem] += 1
+            except Exception as ex:
+                s_dict[elem] = 1
+        for elem in t:
+            try:
+                s_dict[elem] -= 1
+            except Exception as ex:
+                return False
+        return not (any(s_dict.values()))
+
+        '''
+        sol 2
+        Runtime: Beats 72.12% / O(N)
+        Memory: Beats 97.51% / O(1)
+        '''
+        from itertools import zip_longest
+        from collections import defaultdict
+
+        ana_dict = defaultdict(int)
+        for elem1, elem2 in zip_longest(s, t):
+            ana_dict[elem1] += 1
+            ana_dict[elem2] -= 1
+        return not (any(ana_dict.values()))
+
+