[IMP] Two-Pointer-1

3sum.py

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+''' 
+Time Complexity : O(n^2) 
+Space Complexity : O(1) 
+Did this code successfully run on Leetcode : Yes
+Any problem you faced while coding this :  No
+'''
+class Solution:
+    def threeSum(self, nums):
+        n = len(nums)
+        result = []
+        nums.sort()
+        for i in range(n - 2):
+            if i > 0 and nums[i] == nums[i - 1]:
+                continue
+            left = i + 1
+            right = n - 1
+
+            while left < right:
+                total = nums[i] + nums[left] + nums[right]
+
+                if total == 0:
+                    result.append([nums[i], nums[left], nums[right]])
+                    left += 1
+                    right -= 1
+
+                    while left < right and nums[left] == nums[left - 1]:
+                        left += 1
+
+                    while left < right and nums[right] == nums[right + 1]:
+                        right -= 1
+
+                elif total < 0:
+                    left += 1
+                else:
+                    right -= 1
+
+        return result
+
+
+
+s = Solution()
+nums = [-1,0,1,2,-1,-4]
+print(s.threeSum(nums))
+nums = [0,1,1]
+print(s.threeSum(nums))
+nums = [0,0,0]
+print(s.threeSum(nums))

container-with-most-water.py

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+class Solution:
+    '''
+    TC: O(n)
+    SC: O(1)
+    Leetcode: Solved the problem
+    Issue: No issue
+    '''
+    def maxArea(self, height):
+        low = 0
+        high = len(height) - 1
+        res = 0
+        while low <= high:
+            h = min(height[low], height[high])
+            w = high - low
+            res = max(res, h*w)
+            if height[low] < height[high]:
+                low += 1
+            else:
+                high -= 1
+        return res
+
+    '''
+    TC: O(n^2)
+    SC: O(1)
+    '''
+    def maxArea(self, height):
+        n = len(height)
+        res = 0
+        for i in range(n-1):
+            for j in range(1, n):
+                h = min(height[i], height[j])
+                w = j - i
+                res = max(res, h*w)
+        return res
+
+
+s = Solution()
+height = [1,8,6,2,5,4,8,3,7]
+print(s.maxArea(height))
+height = [1,1]
+print(s.maxArea(height))

sort-colors.py

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+''' 
+Time Complexity : O(n) 
+Space Complexity : O(1) 
+Did this code successfully run on Leetcode : Yes
+Any problem you faced while coding this :  No
+'''
+class Solution:
+    def sortColors(self, nums):
+        n = len(nums)
+        low = 0
+        mid = 0
+        high = n - 1
+
+        while mid <= high:
+            if nums[mid] == 2:
+                nums[mid], nums[high] = nums[high], nums[mid]
+                high -= 1
+            elif nums[mid] == 0:
+                nums[mid], nums[low] = nums[low], nums[mid]
+                mid += 1
+                low += 1
+            elif nums[mid] == 1:
+                mid += 1