Bank System, Java - rextester

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//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;

class Rextester {  
    public static void main(String args[]) {
        BankSystem bs = new BankSystem();
        System.out.println(bs.withdraw(0, 100, 0));  // false
        bs.deposit(0, 100, 1);
        bs.withdraw(0, 30, 3);
        bs.deposit(1, 250, 2);
        bs.deposit(1, 2, 7);
        bs.deposit(1, 3, 9);
        System.out.println(Arrays.toString(bs.checkBalance(0, 0, 2))); // 0, 100
        System.out.println(Arrays.toString(bs.checkBalance(1, 3, 8))); // 250, 252
    }
}

/**
 * 设计一个银行帐户系统，实现：
 * 存钱（帐户id，存钱数目，日期）
 * 取钱（帐户id，存钱数目，日期）
 * 查账（帐户id，起始日期，结束日期）： 只需要返回两个数值，一个是起始日期的balance，一个是结束日期的balance。
 * 描述就是这么多，剩下的自己发挥。钱的类型用integer，日期什么的自定义，我直接拿了integer
 */
class BankSystem {
    Map<Integer, List<Record>> store;
    
    public BankSystem() {
        store = new HashMap<>();
    }
    
    public boolean deposit(int id, int amount, int date) {
        if (!store.containsKey(id)) store.put(id, new ArrayList<>());
        List<Record> records = store.get(id);
        Record last = records.size() > 0 ? records.get(records.size() - 1) : null;
        int currentBalance = last == null ? 0 : last.balance;
        if (currentBalance + amount < 0) return false;
        if (last != null && last.date == date) last.balance += amount;
        else records.add(new Record(date, currentBalance + amount));
        return true;
    }
    
    public boolean withdraw(int id, int amount, int date) {
        return deposit(id, -amount, date);
    }
    
    public int[] checkBalance(int id, int startDate, int endDate) {
        return new int[] {checkBalance(id, startDate), checkBalance(id, endDate)};
    }
    
    public int checkBalance(int id, int date) {
        if (!store.containsKey(id)) return 0;
        List<Record> records = store.get(id);
        int i = Collections.binarySearch(records, new Record(date, 0));
        if (i >= 0) return records.get(i).balance;
        i = -i-1;
        return i == 0 ? 0 : records.get(i - 1).balance; 
    }
}

class Record implements Comparable<Record> {
    int date;
    int balance;
    
    public Record(int d, int b) {
        date = d;
        balance = b;
    }
    
    @Override
    public int compareTo(Record that) {
        return this.date - that.date;
    }
}

[ + ] Show input
Compilation time: 1.04 sec, absolute running time: 0.19 sec, cpu time: 0.18 sec, memory peak: 18 Mb, absolute service time: 1,23 sec