判断二叉树是不是满二叉树

package algorithm.tree;

/**
 * 判断二叉树是不是满二叉树
 */
public class IsFull {

    public static boolean isFull(Node node) {
        return process(node).isFull;
    }

    private static ResultInfo process(Node node) {
        if (node == null) {
            return new ResultInfo(true, 0);
        }
        ResultInfo leftInfo = process(node.left);
        ResultInfo rightInfo = process(node.right);
        boolean isFull = leftInfo.isFull && rightInfo.isFull && leftInfo.height == rightInfo.height;
        int height = Math.max(leftInfo.height, rightInfo.height) + 1;
        return new ResultInfo(isFull, height);
    }

    public static boolean isFull1(Node head) {
        if (head == null) {
            return true;
        }
        int height = h(head);
        int nodes = n(head);
        return (1 << height) - 1 == nodes;
    }

    public static int h(Node head) {
        if (head == null) {
            return 0;
        }
        return Math.max(h(head.left), h(head.right)) + 1;
    }

    public static int n(Node head) {
        if (head == null) {
            return 0;
        }
        return n(head.left) + n(head.right) + 1;
    }

    // for test
    public static Node generateRandomBST(int maxLevel, int maxValue) {
        return generate(1, maxLevel, maxValue);
    }

    // for test
    public static Node generate(int level, int maxLevel, int maxValue) {
        if (level > maxLevel || Math.random() < 0.5) {
            return null;
        }
        Node head = new Node((int) (Math.random() * maxValue));
        head.left = generate(level + 1, maxLevel, maxValue);
        head.right = generate(level + 1, maxLevel, maxValue);
        return head;
    }

    public static void main(String[] args) {
        int maxLevel = 5;
        int maxValue = 100;
        int testTimes = 1000000;
        for (int i = 0; i < testTimes; i++) {
            Node head = generateRandomBST(maxLevel, maxValue);
            boolean isFull1 = isFull1(head);
            boolean isFull = isFull(head);
            if (isFull1 != isFull) {
                System.out.println("Oops!");
            }
        }
        System.out.println("finish!");
    }

    /**
     * 向左右子树索要信息
     */
    public static class ResultInfo {

        // 是否是满二叉树
        public boolean isFull;

        // 树高度
        public int height;

        public ResultInfo(boolean isFull, int height) {
            this.isFull = isFull;
            this.height = height;
        }

    }

    /**
     * 二叉树结构
     */
    public static class Node {

        public int value;

        public Node left;

        public Node right;

        public Node(int value) {
            this.value = value;
        }

    }

}

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