[Leo] 5th Week solutions (added rest 3)

Author: leokim0922

3sum/Leo.py

@@ -0,0 +1,26 @@
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+
+        nums.sort()
+        res = []
+
+        for i, ch in enumerate(nums):
+            if i > 0 and nums[i] == nums[i - 1]: continue
+
+            l, r = i + 1, len(nums) - 1
+            while l < r:
+                threeSum = ch + nums[l] + nums[r]
+
+                if threeSum < 0:
+                    l += 1
+                elif threeSum > 0:
+                    r -= 1
+                else:
+                    res.append([ch, nums[l], nums[r]])
+                    l += 1
+                    while l < r and nums[l] == nums[l - 1]:
+                        l += 1
+
+        return res
+
+        ## TC: O(n^2), SC: O(1)

longest-consecutive-sequence/Leo.py

@@ -0,0 +1,16 @@
+class Solution:
+    def longestConsecutive(self, nums: List[int]) -> int:
+
+        seen = set(nums)
+        longest = 0
+
+        for n in seen:
+            if (n - 1) not in seen:
+                length = 1
+
+                while (n + length) in seen:
+                    length += 1
+
+                longest = max(length, longest)
+
+        return longest

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

@@ -0,0 +1,16 @@
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        length = len(nums)
+        res = [1] * length
+        ltor = 1
+        rtol = 1
+
+        for i in range(length):
+            res[i] *= ltor
+            ltor = ltor * nums[i]
+            res[length - i - 1] *= rtol
+            rtol = rtol * nums[length - i - 1]
+
+        return res
+
+        ## TC: O(n), SC: O(1)