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LeetCode: Clone Binary Tree With Random Pointer


Recursive algorithms with a map for ‘Clone Binary Tree With Random Pointer’


Deep copy

Deep copy is a process in which the copying process occurs recursively. We need to clone all the elements of a tree.


The overall algorithm is recursive, but we need to find the previous cloned elements. So use a hashmap will help us to store the pair relationship of the elements of source tree and the new cloned elements.

class Solution {
map<Node*, NodeCopy*> node_map;

NodeCopy* copyRandomBinaryTree(Node* root) {
if(root == NULL) return NULL;
return dfs(root);

NodeCopy* dfs(Node* cur) {
if(cur == NULL) return NULL;
return node_map[cur];
NodeCopy* node = new NodeCopy(cur->val);
node_map[cur] = node;
node->left = dfs(cur->left);
node->right = dfs(cur->right);
node->random = dfs(cur->random);
return node;

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