3 sum solution

Author: devyejin

3sum/devyejin.py

@@ -0,0 +1,36 @@
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        nums.sort() # O(n)
+
+        n = len(nums)
+        result = []
+
+        for i in range(n - 2):
+            # target을 잡을때도 이전에 구했다면 패스
+            if i > 0 and nums[i] == nums[i - 1]:
+                continue
+
+            target = - nums[i]
+            left, right = i + 1, n - 1
+
+            while left < right:
+                two_sum = nums[left] + nums[right]
+
+                if two_sum == target:
+                    result.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 two_sum < target:
+                    left += 1
+                else:
+                    right -= 1
+
+        return result