Create Day-26_Verify Preorder Serialization of a Binary Tree.py

Author: Ram-95

Leetcode_30day_challenge/August_Challenge_2021/Day-26_Verify Preorder Serialization of a Binary Tree.py

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+class Solution(object):
+    def isValidSerialization(self, preorder):
+        """
+        :type preorder: str
+        :rtype: bool
+        """
+        # remember how many empty slots we have
+        # non-null nodes occupy one slot but create two new slots
+        # null nodes occupy one slot
+        
+        p = preorder.split(',')
+        
+        #initially we have one empty slot to put the root in it
+        slot = 1
+        for node in p:
+            
+            # no empty slot to put the current node
+            if slot == 0:
+                return False
+                
+            # a null node?
+            if node == '#':
+                # ocuppy slot
+                slot -= 1
+            else:
+                # create new slot
+                slot += 1
+        
+        #we don't allow empty slots at the end
+        return slot==0