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-rw-r--r--create_bt_from_desc.cpp40
-rw-r--r--create_bt_from_desc.py54
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]]))