11.8 实现数据结构和算法支持track和rank操作。

public class Solution {
    private static RankNode root = null;

    public static void track(int number) {
        if (root == null) {
            root = new RankNode(number);
        } else {
            root.insert(number);
        }
    }

    public static int getRankOfNumber(int number) {
        return root.getRank(number);
    }

    public static void main(String[] args) {
        track(20);
        track(15);
        track(25);
        track(10);
        track(23);
        track(5);
        track(13);
        track(24);
        System.out.println(getRankOfNumber(20));
        System.out.println(getRankOfNumber(15));
        System.out.println(getRankOfNumber(8));

    }
}

class RankNode {
    int val;
    int leftSize;
    RankNode left;
    RankNode right;

    public RankNode(int v) {
        val = v;
    }

    public void insert(int t) {
        if (t <= val) {
            if (left != null) {
                left.insert(t);
            } else {
                left = new RankNode(t);
            }
            leftSize++;
        } else {
            if (right != null) {
                right.insert(t);
            } else {
                right = new RankNode(t);
            }
        }
    }

    public int getRank(int t) {
        if (t == val) {
            return leftSize;
        } else if (t < val) {
            if (left == null)
                return -1;
            else
                return left.getRank(t);
        } else {
            if (right == null)
                return -1;
            else {
                return right.getRank(t) + leftSize + 1;
            }
        }

    }

}