【剑指offer-Java版】39二叉树的深度

二叉树的深度：递归

判断二叉树是否是平衡二叉树:注意二叉树平衡代表的是所有非叶子节点都是一棵平衡树 – 而不仅仅是根节点

    public class _Q39<T> {

    public int TreeDepth(BinaryTreeNode<?> tree){
        if(tree == null) return 0;

        if(tree.leftChild == null && tree.rightChild == null) return 1;

        int left = TreeDepth(tree.leftChild);
        int right = TreeDepth(tree.rightChild);

        return (left > right ? left : right) + 1;
    }


    public boolean IsBalance(BinaryTreeNode<?> tree, int depth[]){
        if(tree == null) return true;

        int depthL[] = {0};
        int depthR[] = {0};
        // 相当于后序遍历
        if(IsBalance(tree.leftChild, depthL) && IsBalance(tree.rightChild, depthR)){
            int diff = depthL[0] - depthR[0];
            if(diff <= 1 && diff >= -1){
                depth[0] = (depthL[0] > depthR[0] ? depthL[0] : depthR[0]) + 1;
                return true;
            }
        }

        return false;
    } 


    }

测试代码：

    public class _Q39Test extends TestCase {

    _Q39<?> treeJudge = new _Q39();

    public void test(){
        BinaryTreeNode<Integer> root = new BinaryTreeNode<>();
        BinaryTreeNode<Integer> node1 = new BinaryTreeNode<>();
        BinaryTreeNode<Integer> node2 = new BinaryTreeNode<>();
        BinaryTreeNode<Integer> node3 = new BinaryTreeNode<>();
        BinaryTreeNode<Integer> node4 = new BinaryTreeNode<>();
        BinaryTreeNode<Integer> node5 = new BinaryTreeNode<>();
        BinaryTreeNode<Integer> node6 = new BinaryTreeNode<>();

        root.value = 10;
        node1.value = 6;
        node2.value = 14;
        node3.value = 4;
        node4.value = 8;
        node5.value = 12;
        node6.value = 16;

        root.leftChild = node1;
        root.rightChild = node2;
        //root.rightChild = null;
        node1.leftChild = node3;
        node1.rightChild = node4;
        node2.leftChild = node5;
        node2.rightChild = node6;

        node3.leftChild = null; node3.rightChild = null;
        node4.leftChild = null; node4.rightChild = null;
        node5.leftChild = null; node5.rightChild = null;
        node6.leftChild = null; node6.rightChild = null;

        System.out.println(treeJudge.TreeDepth(root));
        int depth[] = {0};
        System.out.println(treeJudge.IsBalance(root, depth));
    }
    }