Macro yanfeng42

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I may be slow to respond.

I don't admit there are any other signs of nobility other than kindness.

yanfeng42 / FindGhost.java

Last active November 8, 2021 02:13

algs4 1.3.3 计算不可能产生的出栈顺序 -- 用编码的方式计算

	package life.yanfeng.study.algorithm;

	import edu.princeton.cs.algs4.StdOut;

	import java.util.Arrays;

	enum StackActionEnum {
	pop, push
	}

yanfeng42 / Rational.java

Created October 27, 2021 02:41

alg4 1.2.16 实现一个简易的分数计算工具类

	package life.yanfeng.study.algorithm;

	import edu.princeton.cs.algs4.StdOut;

	// for 1.2.16
	public class Rational {
	// 分子.
	private long numerator;

	// 计算最大公约数. ref: https://zh.wikipedia.org/wiki/%E8%BC%BE%E8%BD%89%E7%9B%B8%E9%99%A4%E6%B3%95

yanfeng42 / SmartDate.java

Created October 15, 2021 02:16

algs4: 1.2.12 使用蔡勒公式计算今天星期几

	package life.yanfeng.study.algorithm;

	import edu.princeton.cs.algs4.StdOut;

	public class SmartDate {
	private final int month;
	private final int day;
	private final int year;
	public SmartDate(int m, int d, int y) throws RuntimeException
	{

yanfeng42 / same-parity.scm

Created September 30, 2021 09:25

same-parity: 不借助辅助函数的特殊 “超纲” 写法

	; 基础方法
	(define (same-parity x . l)
	(same-parity-adpater x l)
	)

	(define (same-parity-adpater x l)
	(if (null? l)
	(cons x l)
	(let ((car-item (car l)))
	(if (even? (+ car-item x))

yanfeng42 / SmartDate.java

Created September 29, 2021 02:02

SmartDate 有感: 我支持所有异常都是受检异常

	package life.yanfeng.study.algorithm;

	import edu.princeton.cs.algs4.StdOut;

	public class SmartDate {
	private final int month;
	private final int day;
	private final int year;
	public SmartDate(int m, int d, int y) throws RuntimeException
	{

yanfeng42 / view_money_order.scm

Last active September 10, 2021 12:41

sicp 2.19: 可视化的方式, 展示零钱本身的顺序, 对计算过程的不同影响.

yanfeng42 / mul-interval-2.scm

Last active August 30, 2021 05:45

sicp 2.11 没有完全符合要求的答案

	; (define (mul-interval x y)
	; (let ((p1 (* (lower-bound x) (lower-bound y)))
	; (p2 (* (lower-bound x) (upper-bound y)))
	; (p3 (* (upper-bound x) (lower-bound y)))
	; (p4 (* (upper-bound x) (upper-bound y)))
	; )
	; (make-interval (min p1 p2 p3 p4) (max p1 p2 p3 p4))
	; )
	; )

yanfeng42 / BinarySearchCase.java

Created August 27, 2021 02:44

1.1.39 关于随机数碰撞的警示

	package life.yanfeng.study.algorithm;

	import edu.princeton.cs.algs4.In;
	import edu.princeton.cs.algs4.StdOut;

	import java.util.Arrays;
	import java.util.Random;
	import java.util.concurrent.ThreadLocalRandom;

	// for 1.1.39

yanfeng42 / church.scm

Created August 26, 2021 04:41

2.6 Church计数: 不使用数字的计算法

	(define zero (lambda (f) (lambda (x) x)))

	(define one (lambda (f) (lambda (x) (f x))))

	(define two (lambda (f) (lambda (x) (f (f x)))))

	(define three (lambda (f) (lambda (x) (f (f (f x))))))

	(define (add m n)
	(lambda (f) (lambda (x) ((m f) ((n f) x))))

yanfeng42 / my-cons.scm

Created August 19, 2021 06:54

2.1.3 有感: 在支持函数作为第一对象的语言里, 可以直接使用 “过程” 定义 “数据”