[:solved] two problems

Author: ppxyn1

3sum/ppxyn1.py

@@ -0,0 +1,32 @@
+# idea: sorting + two pointer
+# The idea was straightforward, but remove the duplication logic was the tricky.
+
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        nums.sort()
+        n = len(nums)
+        answer = []
+
+        for i in range(n):
+            if i > 0 and  nums[i] == nums[i-1]:
+                continue
+
+            left, right = i+1, n-1
+
+            while left < right:
+                s = nums[i] + nums[left] + nums[right]
+                if s == 0:
+                    answer.append([nums[i], nums[left], nums[right]])
+                    while left < right and nums[left] == nums[left+1]:
+                        left += 1
+                    while left < right and nums[right] == nums[right-1]:
+                        right -= 1
+                    left += 1
+                    right -= 1
+                elif s < 0:
+                    left += 1
+                else:
+                    right -= 1
+        return answer
+
+

product-of-array-except-self/ppxyn1.py

@@ -0,0 +1,17 @@
+# idea: O(n) - There is no multiplication calculate it as O(1) / addition is possible
+
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        length = len(nums)
+        answer = [1] * length
+        
+        prefix,suffix = 1,1
+        for i in range(length):       
+            answer[i] = prefix
+            prefix *= nums[i]
+        for j in range(length - 1, -1, -1):  
+            answer[j] *= suffix
+            suffix *= nums[j]
+        return answer
+    
+