Class Solution
Medium
One way to serialize a binary tree is to use preorder traversal. When we encounter a non-null node, we record the node’s value. If it is a null node, we record using a sentinel value such as '#'
.
For example, the above binary tree can be serialized to the string "9,3,4,#,#,1,#,#,2,#,6,#,#"
, where '#'
represents a null node.
Given a string of comma-separated values preorder
, return true
if it is a correct preorder traversal serialization of a binary tree.
It is guaranteed that each comma-separated value in the string must be either an integer or a character '#'
representing null pointer.
You may assume that the input format is always valid.
- For example, it could never contain two consecutive commas, such as
"1,,3"
.
**Note: **You are not allowed to reconstruct the tree.
Example 1:
Input: preorder = “9,3,4,#,#,1,#,#,2,#,6,#,#”
Output: true
Example 2:
Input: preorder = “1,#”
Output: false
Example 3:
Input: preorder = “9,#,#,1”
Output: false
Constraints:
1 <= preorder.length <= 104
preorder
consist of integers in the range[0, 100]
and'#'
separated by commas','
.
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Constructor Summary
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Method Summary
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Constructor Details
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Solution
public Solution()
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Method Details
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isValidSerialization
public boolean isValidSerialization(java.lang.String preorder)
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