【剑指offer-Java版】39二叉树的深度

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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));    }    }

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