先序遍历
public class Codec {
// Encodes a tree to a single string.
public String serialize(TreeNode root) {
if(root == null) return "null";
String left = serialize(root.left);
String right = serialize(root.right);
return root.val + "," + left + "," + right;
}
// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
Deque<String> dq = new ArrayDeque<>(Arrays.asList(data.split(",")));
return deserialize(dq);
}
TreeNode deserialize(Deque<String> dq) {
String cur = dq.poll();
if(cur.equals("null")) return null;
TreeNode root = new TreeNode(Integer.valueOf(cur));
root.left = deserialize(dq);
root.right = deserialize(dq);
return root;
}
}层序遍历
public class Codec {
// Encodes a tree to a single string.
public String serialize(TreeNode root) {
if(root == null) return "null";
StringBuilder sb = new StringBuilder();
Deque<TreeNode> queue = new LinkedList<>();
queue.offer(root);
while(!queue.isEmpty()){
TreeNode cur = queue.poll();
if(cur == null){
sb.append("null,");
continue;
}
sb.append(cur.val + ",");
queue.offer(cur.left);
queue.offer(cur.right);
}
return sb.toString();
}
// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
if(data.equals("null")) return null;
Deque<String> q1 = new ArrayDeque<>(Arrays.asList(data.split(",")));
TreeNode root = new TreeNode(Integer.valueOf(q1.poll()));
Deque<TreeNode> q2 = new ArrayDeque<>();
q2.offer(root);
while(!q1.isEmpty()){
TreeNode cur = q2.poll();
String left = q1.poll();
String right = q1.poll();
if(!left.equals("null")){
cur.left = new TreeNode(Integer.valueOf(left));
q2.offer(cur.left);
}
if(!right.equals("null")){
cur.right = new TreeNode(Integer.valueOf(right));
q2.offer(cur.right);
}
}
return root;
}
}
