Populating Next Right Pointers in Each Node

recursion programming

画图看特点

public class Solution {
    public void connect(TreeLinkNode root) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(root == null)
            return;
        if(root.left != null)
            root.left.next = root.right;
        if(root.right != null)
            root.right.next = root.next == null?null:root.next.left;
        connect(root.left);
        connect(root.right);
    }
}