Week02 Solutions

Author: HYUNAHKO

climbing-stairs/HYUNAHKO.py

@@ -0,0 +1,27 @@
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        if (n<1 or n>45):
+            return 0
+        
+        def factorial(num):
+            if num <= 1:
+                return 1
+            
+            result = 1 
+            for i in range(2, num+1):
+                result *= i
+            return result 
+
+        steps = 0
+        cur_steps = 1
+        quotient = n // 2
+        k=0
+       
+        for _ in range(quotient+1):  
+            cur_steps = factorial(n-k) / (factorial(k)*factorial(n-2*k))  
+            k+=1
+            steps += cur_steps
+
+        return int(steps)
+
+

product-of-array-except-self/HYUNAHKO.py

@@ -0,0 +1,40 @@
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        n = len(nums)
+        result_list = [0] * n
+        if len(nums) <2 or len(nums) > 1e5:
+            return None 
+        
+        p = 1
+        for i in range(n):
+            result_list[i] = p
+            p *= nums[i] 
+            
+        p = 1
+        for i in range(n - 1, -1, -1): 
+            result_list[i] *= p
+            p *= nums[i] 
+            
+        return result_list
+        
+    
+
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        result_list = [0] * len(nums)
+        if len(nums) <2 or len(nums) > 1e5:
+            return None 
+        
+        for idx in range(0, len(nums)):
+            result = 1
+            for idx_left in range(0, idx):
+                result *= nums[idx_left]
+
+            for idx_right in range(idx+1, len(nums)):
+                result *= nums[idx_right]
+            
+            result_list[idx] = result
+
+
+        return result_list
+        

valid-anagram/HYUNAHKO.py

@@ -0,0 +1,25 @@
+from collections import Counter
+
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        letter_dict1 = {}
+        letter_dict2 = {}
+        letter_list1 = list(s)
+        letter_list2 = list(t)
+        
+        for i in letter_list1:
+            letter_dict1[i] = letter_dict1.get(i, 0) + 1
+            
+        for j in letter_list2:
+            letter_dict2[j] = letter_dict2.get(j, 0) + 1
+
+        if (letter_dict1 == letter_dict2):
+            return True 
+        else: 
+            return False
+                
+
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        return Counter(s) == Counter(t)
+