完全二叉树插入

题目：给一颗完全二叉树，要求插入一个节点后，依然是完全二叉树。
分析：利用完全二叉树的性质，找到要插入的位置，先判断左子树的最右结点与右子树的最左结点高度，如果相等，只需要插入到左子树即可，否则插入右子树。

实现：

/**题目：给完全二叉树插入一个节点，插完后保证还是完全二叉树
 * @author ShaoCheng
 * @version 1.0 2015-9-24
 */

class TreeNode{
    int val;
    TreeNode left, right;
    TreeNode(int key){
        val = key;
    }
}

public class Main {
    public static void main(String[] args){
        TreeNode p1 = new TreeNode(1);
        TreeNode p2 = new TreeNode(2);
        TreeNode p3 = new TreeNode(3);
        TreeNode p4 = new TreeNode(4);
        p1.left = p2;
        p1.right = p3;
        p2.left = p4;

        TreeNode node = new TreeNode(100);
        TreeNode root = insertBinary(p1, node);
        printTree(root);
    }

    //中序遍历
    public static void printTree(TreeNode root){
        if(root == null)
            return;
        System.out.println(root.val);
        printTree(root.left);
        printTree(root.right);
    }

    public static TreeNode insertBinary(TreeNode root, TreeNode node){
        if(root == null)
            return node;
        else if(node == null)
            return root;
        if(root.left == null){
            root.left = node;
            return root;
        }
        else if(root.right == null){
            root.right = node;
            return root;
        }

        int lrh = 0;
        int rrh = 0;
        TreeNode pNode = root.left;
        while(pNode != null){
            lrh++;
            pNode = pNode.right;
        }

        pNode = root.right;
        while(pNode != null){
            rrh++;
            pNode = pNode.left;
        }

        if(lrh != rrh){
            insertBinary(root.right, node);
        }
        else
            insertBinary(root.left, node);
        return root;
    }
}