Binary Tree Pruning Problem
Description
LeetCode Problem 814.
Given the root of a binary tree, return the same tree where every subtree (of the given tree) not containing a 1 has been removed.
A subtree of a node node is node plus every node that is a descendant of node.
Example 1:
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Input: root = [1,null,0,0,1]
Output: [1,null,0,null,1]
Explanation:
Only the red nodes satisfy the property "every subtree not containing a 1".
The diagram on the right represents the answer.
Example 2:
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Input: root = [1,0,1,0,0,0,1]
Output: [1,null,1,null,1]
Example 3:
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Input: root = [1,1,0,1,1,0,1,0]
Output: [1,1,0,1,1,null,1]
Constraints:
- The number of nodes in the tree is in the range [1, 200].
- Node.val is either 0 or 1.
Sample C++ Code
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/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
TreeNode* pruneTree(TreeNode* root) {
if (root == NULL)
return NULL;
if (root->left != NULL) {
root->left = pruneTree(root->left);
}
if (root->right != NULL) {
root->right = pruneTree(root->right);
}
if ((root->left == NULL) && (root->right == NULL)) {
if (root->val == 0)
return NULL;
else
return root;
}
return root;
}
};