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leetcode297.java
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leetcode297.java
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/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Codec {
private final String delimiter = ",";
private final String emptyNode = "#";
// Encodes a tree to a single string.
public String serialize(TreeNode root) {
StringBuilder sb = new StringBuilder();
serializeHelper(root, sb);
return sb.toString();
}
private void serializeHelper(TreeNode root, StringBuilder sb){
if(root == null){
sb.append(emptyNode).append(delimiter);
}
else{
sb.append(root.val).append(delimiter);
serializeHelper(root.left, sb);
serializeHelper(root.right, sb);
}
}
// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
Deque<String> res = new LinkedList<>();
res.addAll(Arrays.asList(data.split(delimiter)));
return deserializeHelper(res);
}
private TreeNode deserializeHelper(Deque<String> nodes){
String nodeVal = nodes.pollFirst();
if(nodeVal.equals(emptyNode)){
return null;
}
else{
TreeNode node = new TreeNode(Integer.parseInt(nodeVal));
node.left = deserializeHelper(nodes);
node.right = deserializeHelper(nodes);
return node;
}
}
}
// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.deserialize(codec.serialize(root));