[yeoju] Week 9

find-minimum-in-rotated-sorted-array/aa601.py

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+'''
+TC: O(log n)
+SC: O(1)
+'''
+
+class Solution:
+    def findMin(self, nums: List[int]) -> int:
+        left = 0
+        right = len(nums) - 1
+        mid = (left + right) // 2
+        while left < right:
+            mid = (left + right) // 2
+            if nums[mid] > nums[right]:
+                left = mid + 1
+            else:
+                right = mid
+        return nums[left]

linked-list-cycle/aa601.py

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+'''
+    TC : O(n)
+    SC : O(n)
+'''
+class Solution:
+    def hasCycle(self, head: Optional[ListNode]) -> bool:
+        tmp = head
+        visited = set()
+        while tmp:
+            if tmp in visited:
+                return True
+            visited.add(tmp)
+            tmp = tmp.next
+        return False

maximum-product-subarray/aa601.py

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+'''
+TC : O(n)
+SC : O(1)
+'''
+
+class Solution:
+    def maxProduct(self, nums: list[int]) -> int:
+        max_prod = nums[0]
+        min_prod = nums[0]
+        result = nums[0]
+        for i in range(1, len(nums)):
+            max_prod, min_prod = max(nums[i], nums[i] * max_prod, nums[i] * min_prod), min(nums[i], nums[i] * min_prod, nums[i] * max_prod)
+            result = max(result, max_prod)
+        return result

pacific-atlantic-water-flow/aa601.py

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+'''
+TC: O(r * c)
+SC: O(r * c)
+'''
+
+class Solution:
+	def pacificAtlantic(self, heights: list[list[int]]) -> list[list[int]]:
+		r_size = len(heights)
+		c_size = len(heights[0])
+		pcf = set()
+		atl = set()
+
+		def recur(visited, row, col) -> None :
+			if (row, col) in visited:
+				return
+			visited.add((row, col))
+			for r, c in ([row + 1, col], [row - 1, col], [row, col + 1], [row, col - 1]):
+				if 0 <= r < r_size and 0 <= c < c_size \
+					and heights[r][c] >= heights[row][col]:
+					recur(visited, r, c)
+		for r in range(r_size):
+			recur(pcf, r, 0)
+			recur(atl, r, c_size - 1)
+		for c in range(c_size):
+			recur(pcf, 0, c)
+			recur(atl, r_size - 1, c)
+		result = [[r, c] for r, c in pcf & atl]
+		return result