536 Construct Binary Tree from String
536. Construct Binary Tree from String
1. Question
You need to construct a binary tree from a string consisting of parenthesis and integers.
The whole input represents a binary tree. It contains an integer followed by zero, one or two pairs of parenthesis. The integer represents the root's value and a pair of parenthesis contains a child binary tree with the same structure.
You always start to construct theleftchild node of the parent first if it exists.
Example:
Note:
There will only be
'('
,')'
,'-'
and'0'
~'9'
in the input string.An empty tree is represented by
""
instead of"()"
.
2. Implementation
(1) Recursion
(2) Iteration
3. Time & Space Complexity
Recursion: 时间复杂度O(n), 空间复杂度O(n)
Iteration: 时间复杂度O(n), 空间复杂度O(n)
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