Question:
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public TreeNode inorderSuccessor(TreeNode root, TreeNode p) {
if(p.right != null){
return minNode(p.right);
}
TreeNode succ = null;
// Start from root and search for successor down the tree
while(root!= null){
if(p.val < root.val){
succ = root;
root = root.left;
}
else if(p.val > root.val){
root = root.right;
}
else{
break;
}
}
return succ;
}
public TreeNode minNode(TreeNode root){
if(root==null)return null;
TreeNode q = root;
TreeNode p = root.left;
while(p!=null){
q=p;
p=p.left;
}
return q;
}
}
Friday, November 6, 2015
Serialize and Deserialize Binary Tree -- Leetcode
Question:
Answer:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Codec {
private StringBuilder str = new StringBuilder();
// Encodes a tree to a single string.
public String serialize(TreeNode root) {
StringBuilder sb = new StringBuilder();
serialize(root, sb);
return sb.toString();
}
public void serialize(TreeNode root, StringBuilder sb){
if(root==null){
str.append("# ");
}
str.append(root.val + " ");
serialize(root.left, sb);
serialize(root.right, sb);
}
// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
if(data==null || data.length()==0){
return null;
}
StringTokenizer st = new StringTokenizer(data, " ");
return deserialize(st);
}
public TreeNode deserialize(StringTokenizer st){
if(!st.hasMoreTokens()){
return null;
}
String str_val = st.nextToken();
if(str_val.equals("#")){
return null;
}
TreeNode root = new TreeNode(Integer.parseInt(str_val));
root.left = deserialize(st);
root.right = deserialize(st);
return root;
}
}
// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.deserialize(codec.serialize(root));
Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.
Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.
For example, you may serialize the following tree
1 / \ 2 3 / \ 4 5as
"[1,2,3,null,null,4,5]"
, just the same as how LeetCode OJ serializes a binary tree. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.Answer:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Codec {
private StringBuilder str = new StringBuilder();
// Encodes a tree to a single string.
public String serialize(TreeNode root) {
StringBuilder sb = new StringBuilder();
serialize(root, sb);
return sb.toString();
}
public void serialize(TreeNode root, StringBuilder sb){
if(root==null){
str.append("# ");
}
str.append(root.val + " ");
serialize(root.left, sb);
serialize(root.right, sb);
}
// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
if(data==null || data.length()==0){
return null;
}
StringTokenizer st = new StringTokenizer(data, " ");
return deserialize(st);
}
public TreeNode deserialize(StringTokenizer st){
if(!st.hasMoreTokens()){
return null;
}
String str_val = st.nextToken();
if(str_val.equals("#")){
return null;
}
TreeNode root = new TreeNode(Integer.parseInt(str_val));
root.left = deserialize(st);
root.right = deserialize(st);
return root;
}
}
// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.deserialize(codec.serialize(root));
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