Merge pull request neetcode-gh#2372 from ksfkwan/patch-1

Update 0015-3sum.py

Author: MHamiid

python/0015-3sum.py

@@ -1,27 +1,27 @@
 class Solution:
-    def threeSum(self, nums: List[int]) -> List[List[int]]:
-        res = []
-        nums.sort()
-
-        for i, a in enumerate(nums):
-            # Skip positive integers
-            if a > 0:
+    def ThreeSum(self, integers):
+        """
+        :type integers: List[int]
+        :rtype: List[List[int]]
+        """
+        integers.sort()
+        result = []
+        for index in range(len(integers)):
+            if integers[index] > 0:
                 break
-
-            if i > 0 and a == nums[i - 1]:
+            if index > 0 and integers[index] == integers[index - 1]:
                 continue
-
-            l, r = i + 1, len(nums) - 1
-            while l < r:
-                threeSum = a + nums[l] + nums[r]
-                if threeSum > 0:
-                    r -= 1
-                elif threeSum < 0:
-                    l += 1
+            left, right = index + 1, len(integers) - 1
+            while left < right:
+                if integers[left] + integers[right] < 0 - integers[index]:
+                    left += 1
+                elif integers[left] + integers[right] > 0 - integers[index]:
+                    right -= 1
                 else:
-                    res.append([a, nums[l], nums[r]])
-                    l += 1
-                    r -= 1
-                    while nums[l] == nums[l - 1] and l < r:
-                        l += 1
-        return res
+                    result.append([integers[index], integers[left], integers[right]]) # After a triplet is appended, we try our best to incease the numeric value of its first element or that of its second.
+                    left += 1 # The other pairs and the one we were just looking at are either duplicates or smaller than the target.
+                    right -= 1 # The other pairs are either duplicates or greater than the target.
+                    # We must move on if there is less than or equal to one integer in between the two integers.
+                    while integers[left] == integers[left - 1] and left < right:
+                        left += 1 # The pairs are either duplicates or smaller than the target.
+        return result