[printjin-gmailcom] Week 13 Solutions

find-median-from-data-stream/printjin-gmailcom.py

@@ -0,0 +1,15 @@
+import heapq
+
+class MedianFinder:
+    def __init__(self):
+        self.low = []
+        self.high = [] 
+    def addNum(self, num):
+        heapq.heappush(self.low, -num)
+        heapq.heappush(self.high, -heapq.heappop(self.low))
+        if len(self.high) > len(self.low):
+            heapq.heappush(self.low, -heapq.heappop(self.high))
+    def findMedian(self):
+        if len(self.low) > len(self.high):
+            return -self.low[0]
+        return (-self.low[0] + self.high[0]) / 2

insert-interval/printjin-gmailcom.py

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+class Solution:
+    def insert(self, intervals, newInterval):
+        result = []
+        i = 0
+        n = len(intervals)
+        while i < n and intervals[i][1] < newInterval[0]:
+            result.append(intervals[i])
+            i += 1
+        while i < n and intervals[i][0] <= newInterval[1]:
+            newInterval[0] = min(newInterval[0], intervals[i][0])
+            newInterval[1] = max(newInterval[1], intervals[i][1])
+            i += 1
+        result.append(newInterval)
+        while i < n:
+            result.append(intervals[i])
+            i += 1
+        return result

kth-smallest-element-in-a-bst/printjin-gmailcom.py

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+class Solution:
+    def kthSmallest(self, root, k):
+        self.count = 0
+        self.result = 0
+        def inorder(node):
+            if not node:
+                return
+            inorder(node.left)
+            self.count += 1
+            if self.count == k:
+                self.result = node.val
+                return
+            inorder(node.right)
+        inorder(root)
+        return self.result

lowest-common-ancestor-of-a-binary-search-tree/printjin-gmailcom.py

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+class Solution:
+    def lowestCommonAncestor(self, root, p, q):
+        while root:
+            if p.val < root.val and q.val < root.val:
+                root = root.left
+            elif p.val > root.val and q.val > root.val:
+                root = root.right
+            else:
+                return root

meeting-rooms/printjin-gmailcom,.py

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+from typing import List
+
+class Solution:
+    def canAttendMeetings(self, intervals: List[Interval]) -> bool:
+        intervals.sort(key=lambda x: x.start)
+        for i in range(1, len(intervals)):
+            if intervals[i].start < intervals[i - 1].end:
+                return False
+        return True