Solve 977 Squares of a Sorted Array

python/977_squares_of_a_sorted_array.py

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+class Solution:
+    def sortedSquares(self, nums: List[int]) -> List[int]:
+        negative_end = 0
+        while negative_end < len(nums) and nums[negative_end] < 0:
+            negative_end += 1
+
+        return self.merge(
+            [x ** 2 for x in reversed(nums[:negative_end])],
+            [x ** 2 for x in nums[negative_end:]]
+        )
+    
+    def merge(self, list1: List[int], list2: List[int]) -> List[int]:
+        left1 = 0
+        left2 = 0
+        new = []
+
+        while left1 < len(list1) and left2 < len(list2):
+            if list1[left1] < list2[left2]:
+                new.append(list1[left1])
+                left1 += 1
+            else:
+                new.append(list2[left2])
+                left2 += 1
+
+        while left1 < len(list1):
+            new.append(list1[left1])
+
+        while left2 < len(list2):
+            new.append(list1[left1])
+
+        return new
+
+
+"""
+Alternative solution with the work done manually to save on unneeded copying
+
+class Solution:
+    def sortedSquares(self, nums: List[int]) -> List[int]:
+        l = len(nums)
+
+        negative_end = 0
+        while negative_end < l and nums[negative_end] < 0:
+            negative_end += 1
+        
+        # Square the array
+        for i in range(l):
+            nums[i] = nums[i] ** 2
+
+        # Reverse the negative part of the array
+        for i in range(negative_end // 2):
+            nums[i], nums[negative_end-i-1] = nums[negative_end-i-1], nums[i]
+        
+
+        # Merge the parts together
+        new = []
+
+        left = 0
+        right = negative_end
+
+        while left < negative_end and right < l:
+            if nums[left] < nums[right]:
+                new.append(nums[left])
+                left += 1
+            else:
+                new.append(nums[right])
+                right += 1
+
+        while left < negative_end:
+            new.append(nums[left])
+            left += 1
+
+        while right < l:
+            new.append(nums[right])
+            right += 1
+
+        return new
+
+"""