Create addNum

addNum

@@ -0,0 +1,22 @@
+class MedianFinder:
+  def __init__(self):
+    self.maxHeap = []
+    self.minHeap = []
+
+  def addNum(self, num: int) -> None:
+    if not self.maxHeap or num <= -self.maxHeap[0]:
+      heapq.heappush(self.maxHeap, -num)
+    else:
+      heapq.heappush(self.minHeap, num)
+
+    # Balance two heaps s.t.
+    # |maxHeap| >= |minHeap| and |maxHeap| - |minHeap| <= 1
+    if len(self.maxHeap) < len(self.minHeap):
+      heapq.heappush(self.maxHeap, -heapq.heappop(self.minHeap))
+    elif len(self.maxHeap) - len(self.minHeap) > 1:
+      heapq.heappush(self.minHeap, -heapq.heappop(self.maxHeap))
+
+  def findMedian(self) -> float:
+    if len(self.maxHeap) == len(self.minHeap):
+      return (-self.maxHeap[0] + self.minHeap[0]) / 2.0
+    return -self.maxHeap[0]