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-rw-r--r-- | create_bt_from_desc.cpp | 40 | ||||
-rw-r--r-- | create_bt_from_desc.py | 54 |
2 files changed, 94 insertions, 0 deletions
diff --git a/create_bt_from_desc.cpp b/create_bt_from_desc.cpp new file mode 100644 index 0000000..9ad6b4a --- /dev/null +++ b/create_bt_from_desc.cpp @@ -0,0 +1,40 @@ +// 2196. Create Binary Tree From Descriptions +#include "leetcode.h" + +/* + * you are given a 2d integer array 'descriptions' where 'descriptions[i] = + * [parent_i, child_i, isleft_i]' indicates that 'parent_i' is the parent of + * 'child_i', in a binary tree of unique values. construct the binary tree + * described by 'descriptions' and return its root. the test cases will be + * generated such that the binary tree is valid. + */ + +class Solution { +public: + TreeNode *createBinaryTree(vector<vector<int>> &descriptions) { + unordered_map<int, TreeNode *> get_node; + unordered_map<int, bool> is_child; + for (auto &i : descriptions) { + if (!get_node.count(i[0])) { + TreeNode *par = new TreeNode(i[0]); + get_node[i[0]] = par; + } + if (!get_node.count(i[1])) { + TreeNode *child = new TreeNode(i[1]); + get_node[i[1]] = child; + } + if (i[2] == 1) + get_node[i[0]]->left = get_node[i[1]]; + else + get_node[i[0]]->right = get_node[i[1]]; + is_child[i[1]] = true; + } + TreeNode *ans = NULL; + for (auto &i : descriptions) + if (!is_child[i[0]]) { + ans = get_node[i[0]]; + break; + } + return ans; + } +}; diff --git a/create_bt_from_desc.py b/create_bt_from_desc.py new file mode 100644 index 0000000..001f540 --- /dev/null +++ b/create_bt_from_desc.py @@ -0,0 +1,54 @@ +# 2196. Create Binary Tree From Descriptions +from collections import defaultdict + +""" +you are given a 2d integer array 'descriptions' where 'descriptions[i] = +[parent_i, child_i, isleft_i]' indicates that 'parent_i' is the parent of +'child_i', in a binary tree of unique values. construct the binary tree +described by 'descriptions' and return its root. the test cases will be +generated such that the binary tree is valid. +""" + + +# Definition for a binary tree node. +class TreeNode(object): + def __init__(self, val=0, left=None, right=None): + self.val = val + self.left = left + self.right = right + + +class Solution(object): + def createBinaryTree(self, descriptions): + """ + :type descriptions: List[List[int]] + :rtype: Optional[TreeNode] + """ + children = set() + m = {} + for p, c, l in descriptions: + np = m.setdefault(p, TreeNode(p)) + nc = m.setdefault(c, TreeNode(c)) + if l: + np.left = nc + else: + np.right = nc + children.add(c) + root = (set(m) - set(children)).pop() + return m[root] + + +if __name__ == "__main__": + obj = Solution() + print( + obj.createBinaryTree( + descriptions=[ + [20, 15, 1], + [20, 17, 0], + [50, 20, 1], + [50, 80, 0], + [80, 19, 1], + ] + ) + ) + print(obj.createBinaryTree(descriptions=[[1, 2, 1], [2, 3, 0], [3, 4, 1]])) |