题解 | #二叉树的下一个结点#

/*
public class TreeLinkNode {
    int val;
    TreeLinkNode left = null;
    TreeLinkNode right = null;
    TreeLinkNode next = null;

    TreeLinkNode(int val) {
        this.val = val;
    }
}
*/
import java.util.*;
public class Solution {
    private TreeLinkNode ans = null;
    private boolean isFound = false;
    public TreeLinkNode GetNext(TreeLinkNode pNode) {
        TreeLinkNode root = pNode;
        while(root.next != null) {
            root = root.next;
        }
        inOrderTrav(root, pNode);
        return ans;
    }
    private void inOrderTrav(TreeLinkNode root, TreeLinkNode target) {
        if(root == null) {
            return;
        }
        inOrderTrav(root.left, target);
        if(isFound && ans == null) {
            ans = root;
        }
        if(root == target) {
            isFound = true;
        }
        inOrderTrav(root.right, target);
    }
}