Ch10 Lab - 재귀 호출

Code10-01.py

무한 재귀 호출의 개념을 확인합니다

def openBox() :

	print("종이 상자를 엽니다. ^^")
	openBox()

openBox()	# 처음 함수를 다시 호출

Code10-01.py

Demonstrates the concept of infinite recursion

def openBox() :

	print("Opening a paper box. ^^")
	openBox()

openBox()	# First function call again

Code10-02.py

재귀 호출의 종료 조건(기저 조건)을 설정합니다

def openBox() :

	global count
	print("종이 상자를 엽니다. ^^")
	count -= 1
	if count == 0 :
		print("** 반지를 넣고 반환합니다. **")
		return
	openBox()
	print("종이 상자를 닫습니다. ^^")

count = 10
openBox()	# 처음 함수를 다시 호출

Code10-02.py

Sets a base case to terminate recursion

def openBox() :

	global count
	print("Opening a paper box. ^^")
	count -= 1
	if count == 0 :
		print("** Inserts a ring and returns it. **")
		return
	openBox()
	print("Closing a paper box. ^^")

count = 10
openBox()	# First function call again

Code10-03.py

재귀로 1부터 n까지의 합을 구합니다

def addNumber(num) :

    if num <= 1 :
        return 1
    return num + addNumber(num-1)

print(addNumber(10))

Code10-03.py

Calculates the sum from 1 to n using recursion

def addNumber(num) :

    if num <= 1 :
        return 1
    return num + addNumber(num-1)

print(addNumber(10))

Code10-04.py

재귀로 팩토리얼을 계산합니다

def factorial(num) :

	if num <= 1 :
		print('1 반환')
		return 1
	print("%d * %d! 호출" % (num, num-1))
	retVal = factorial(num-1)

	print("%d * %d!(=%d) 반환" % (num, num-1, retVal))
	return num * retVal

print('\n5! = ', factorial(5))

Code10-04.py

Calculates factorial using recursion

def factorial(num) :

	if num <= 1 :
		print('return 1')
		return 1
	print("%d * %d! call" % (num, num-1))
	retVal = factorial(num-1)

	print("%d * %d!(=%d) return" % (num, num-1, retVal))
	return num * retVal

print('\n5! = ', factorial(5))

Code10-05.py

재귀로 카운트다운을 구현합니다

def countDown(n) :

	if n == 0 :
		print('발사!!')
	else :
		print(n)
		countDown(n-1)

countDown(5)

Code10-05.py

Implements a countdown using recursion

def countDown(n) :

	if n == 0 :
		print('Launch!!')
	else :
		print(n)
		countDown(n-1)

countDown(5)

Code10-06.py

재귀로 별 모양 패턴을 출력합니다

def printStar(n) :

	if n > 0 :
		printStar(n-1)
		print('★' * n)

printStar(5)

Code10-06.py

Prints a star pattern using recursion

def printStar(n) :

	if n > 0 :
		printStar(n-1)
		print('★' * n)

printStar(5)

Code10-07.py

재귀로 구구단을 출력합니다

def gugu(dan, num) :

	print("%d x %d = %d" % (dan, num, dan*num))
	if num < 9:
		gugu(dan, num+1)

for dan in range(2,10) :
	print("## %d단 ##" % dan)
	gugu(dan, 1)

Code10-07.py

Prints a multiplication table using recursion

def gugu(dan, num) :

	print("%d x %d = %d" % (dan, num, dan*num))
	if num < 9:
		gugu(dan, num+1)

for dan in range(2,10) :
	print("## %d-dan ##" % dan)
	gugu(dan, 1)

Code10-08.py

재귀로 거듭제곱을 계산합니다

tab = ''
def pow(x, n) :

	global tab
	tab += '	'
	if  n == 0 :
		return 1
	print(tab+"%d*%d^(%d-%d)" % (x, x, n, 1))
	return x * pow (x, n-1)

print('2^4')
print('답 -->', pow(2, 4))

Code10-08.py

Calculates power (exponentiation) using recursion

tab = ''
def pow(x, n) :

	global tab
	tab += '	'
	if  n == 0 :
		return 1
	print(tab+"%d*%d^(%d-%d)" % (x, x, n, 1))
	return x * pow (x, n-1)

print('2^4')
print('answer -->', pow(2, 4))

Code10-09.py

재귀로 배열의 합계를 구합니다

import random

def arySum(arr, n) :

	if n <= 0 :
		return arr[0]
	return arySum(arr, n-1) + arr[n]

ary = [random.randint(0, 255) for _ in range(random.randint(10, 20))]
print(ary)
print('배열 합계 -->', arySum(ary, len(ary)-1))

Code10-09.py

Calculates array sum using recursion

import random

def arySum(arr, n) :

	if n <= 0 :
		return arr[0]
	return arySum(arr, n-1) + arr[n]

ary = [random.randint(0, 255) for _ in range(random.randint(10, 20))]
print(ary)
print('Array sum -->', arySum(ary, len(ary)-1))

Code10-10.py

재귀로 피보나치 수열을 구현합니다

def fibo(n) :

	if n == 0 :
		return 0
	elif n == 1 :
		return 1
	else :
		return fibo(n-1) + fibo(n-2)

print('피보나치 수 --> 0 1 ', end='')
for i in range(2, 20) :
	print(fibo(i), end=' ')

Code10-10.py

Implements the Fibonacci sequence using recursion

def fibo(n) :

	if n == 0 :
		return 0
	elif n == 1 :
		return 1
	else :
		return fibo(n-1) + fibo(n-2)

print('Fibonacci number --> 0 1 ', end='')
for i in range(2, 20) :
	print(fibo(i), end=' ')

Code10-11.py

재귀로 회문(palindrome) 검사를 구현합니다

## 함수 선언 부분 ##
def palindrome(pStr) :

	if len(pStr) <= 1 :
		return True

	if pStr[0] != pStr[-1] :
		return False

	return palindrome(pStr[1:len(pStr)-1])

## 전역 변수 선언 부분 ##
strAry = ["reaver", "kayak", "Borrow or rob", "주유소의 소유주", "야 너 이번주 주번이 너야", "살금 살금"]

## 메인 코드 부분 ##

for testStr in strAry :
	print(testStr, end = '--> ' )
	testStr = testStr.lower().replace(' ','')
	if palindrome(testStr) :
		print('O')
	else :
		print('X')

Code10-11.py

Implements palindrome checking using recursion

## Function Declarations ##
def palindrome(pStr) :

	if len(pStr) <= 1 :
		return True

	if pStr[0] != pStr[-1] :
		return False

	return palindrome(pStr[1:len(pStr)-1])

## Global Variables ##
strAry = ["reaver", "kayak", "Borrow or rob", "Gas station owner", "Hey, you're on duty this week", "tiptoeing"]

## Main Code ##
for testStr in strAry :
	print(testStr, end = '--> ' )
	testStr = testStr.lower().replace(' ','')
	if palindrome(testStr) :
		print('O')
	else :
		print('X')

Code10-12.py

재귀로 프랙탈 트리를 그립니다 (tkinter)

from tkinter import *

window = Tk()
canvas = Canvas(window, height=1000, width=1000, bg='white')
canvas.pack()

cx=1000//2
cy=1000//2
r = 400
canvas.create_oval(cx-r, cy-r, cx+r, cy+r, width=2, outline="red")

window.mainloop()

Code10-12.py

Draws a fractal tree using recursion (tkinter)

from tkinter import *

window = Tk()
canvas = Canvas(window, height=1000, width=1000, bg='white')
canvas.pack()

cx=1000//2
cy=1000//2
r = 400
canvas.create_oval(cx-r, cy-r, cx+r, cy+r, width=2, outline="red")

window.mainloop()

Code10-13.py

재귀로 원형 프랙탈을 그립니다 (tkinter)

from tkinter import *

## 함수 선언 부분 ##
def drawCircle(x, y, r) :

	global count
	count += 1
	canvas.create_oval(x-r, y-r, x+r, y+r)
	canvas.create_text(x, y-r, text=str(count), font=('', 30))
	if r >= radius/2 :
		drawCircle(x-r//2, y, r//2)
		drawCircle(x+r//2, y, r//2)

## 전역 변수 선언 부분 ##
count = 0
wSize = 1000
radius = 400

## 메인 코드 부분 ##

window = Tk()
canvas = Canvas(window, height=wSize, width=wSize, bg='white')

drawCircle(wSize//2, wSize//2, radius)

canvas.pack()
window.mainloop()

Code10-13.py

Draws circular fractals using recursion (tkinter)

from tkinter import *

## Function Declarations ##
def drawCircle(x, y, r) :

	global count
	count += 1
	canvas.create_oval(x-r, y-r, x+r, y+r)
	canvas.create_text(x, y-r, text=str(count), font=('', 30))
	if r >= radius/2 :
		drawCircle(x-r//2, y, r//2)
		drawCircle(x+r//2, y, r//2)

## Global Variables ##
count = 0
wSize = 1000
radius = 400

## Main Code ##
window = Tk()
canvas = Canvas(window, height=wSize, width=wSize, bg='white')

drawCircle(wSize//2, wSize//2, radius)

canvas.pack()
window.mainloop()

Code10-14.py

재귀로 랜덤 프랙탈 아트를 그립니다 (tkinter)

from tkinter import *
import random

## 함수 선언 부분 ##
def drawCircle(x, y, r) :

	canvas.create_oval(x-r, y-r, x+r, y+r, width=2, outline=random.choice(colors))
	if r >= 5 :
		drawCircle(x+r//2, y, r//2)
		drawCircle(x-r//2, y, r//2)

## 전역 변수 선언 부분 ##
colors = ["red", "green", "blue", "black", "orange", "indigo", "violet"]
wSize = 1000
radius = 400

## 메인 코드 부분 ##

window = Tk()
window.title("원 모양의 프랙탈")
canvas = Canvas(window, height=wSize, width=wSize, bg='white')

drawCircle(wSize//2, wSize//2, radius)

canvas.pack()
window.mainloop()

Code10-14.py

Draws random fractal art using recursion (tkinter)

from tkinter import *
import random

## Function Declarations ##
def drawCircle(x, y, r) :

	canvas.create_oval(x-r, y-r, x+r, y+r, width=2, outline=random.choice(colors))
	if r >= 5 :
		drawCircle(x+r//2, y, r//2)
		drawCircle(x-r//2, y, r//2)

## Global Variables ##
colors = ["red", "green", "blue", "black", "orange", "indigo", "violet"]
wSize = 1000
radius = 400

## Main Code ##
window = Tk()
window.title("Circle-shaped fractal")
canvas = Canvas(window, height=wSize, width=wSize, bg='white')

drawCircle(wSize//2, wSize//2, radius)

canvas.pack()
window.mainloop()

Ex10-01.py

재귀 응용: n진법 변환기를 구현합니다

## 함수 선언 부분 ##
def notation(base, n):

	if n < base :
		print(numberChar[n], end = ' ')
	else :
		notation(base, n // base)
		print(numberChar[n % base], end = ' ')

## 전역 변수 선언 부분 ##
numberChar = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
numberChar += ['A', 'B', 'C', 'D', 'E', 'F']

## 메인 코드 부분 ##

number = int(input('10진수 입력 -->'))
print('\n 2진수 : ', end = ' ')
notation(2, number)
print('\n 8진수 : ', end = ' ')
notation(8, number)
print('\n16진수 : ', end = ' ')
notation(16, number)

Ex10-01.py

Recursion application: implements a base-n converter

## Function Declarations ##
def notation(base, n):

	if n < base :
		print(numberChar[n], end = ' ')
	else :
		notation(base, n // base)
		print(numberChar[n % base], end = ' ')

## Global Variables ##
numberChar = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
numberChar += ['A', 'B', 'C', 'D', 'E', 'F']

## Main Code ##
number = int(input('Enter decimal -->'))
print('\n Binary: ', end = ' ')
notation(2, number)
print('\n Octal: ', end = ' ')
notation(8, number)
print('\nHexadecimal: ', end = ' ')
notation(16, number)

Ex10-02.py

재귀 응용: 시에르핀스키 삼각형을 그립니다

from tkinter import *

## 함수 선언 부분 ##
def drawTriangle(x, y, size) :

	if size >= 30 :
		drawTriangle(x, y, size/2)				# 왼쪽 아래 작은 삼각형
		drawTriangle(x+size/2, y, size / 2)			# 오른쪽 아래 작은 삼각형
		drawTriangle(x + size / 4, int(y-size*(3**0.5)/4), size / 2)	# 위쪽 작은 삼각형
	else :
		canvas.create_polygon (x, y, x + size, y, x + size / 2, y - size*(3 ** 0.5) / 2, fill = 'red', outline = "red")

## 전역 변수 선언 부분 ##
wSize = 1000
radius = 400

## 메인 코드 부분 ##

window = Tk()
window.title("삼각형 모양의 프랙탈")
canvas = Canvas(window, height = wSize, width = wSize, bg = 'white')

drawTriangle(wSize/5, wSize/5*4, wSize*2/3)

canvas.pack()
window.mainloop()

Ex10-02.py

Recursion application: draws a Sierpinski triangle

from tkinter import *

## Function Declarations ##
def drawTriangle(x, y, size) :

	if size >= 30 :
		drawTriangle(x, y, size/2)				# Lower-left small triangle
		drawTriangle(x+size/2, y, size / 2)			# Lower-right small triangle
		drawTriangle(x + size / 4, int(y-size*(3**0.5)/4), size / 2)	# Upper small triangle
	else :
		canvas.create_polygon (x, y, x + size, y, x + size / 2, y - size*(3 ** 0.5) / 2, fill = 'red', outline = "red")

## Global Variables ##
wSize = 1000
radius = 400

## Main Code ##
window = Tk()
window.title("Triangle-shaped fractal")
canvas = Canvas(window, height = wSize, width = wSize, bg = 'white')

drawTriangle(wSize/5, wSize/5*4, wSize*2/3)

canvas.pack()
window.mainloop()

Self10-01.py

재귀로 범위 합계를 직접 구현합니다

def addNumber(num1, num2) :

    if num2 <= num1 :
        return num1
    return num2 + addNumber( num1, num2 - 1 )

num1 = int(input('숫자1-->'))
num2 = int(input('숫자2-->'))
if num1 > num2 :
    num1, num2 = num2, num1
print(addNumber(num1, num2))

Self10-01.py

Implements range sum using recursion yourself

def addNumber(num1, num2) :

    if num2 <= num1 :
        return num1
    return num2 + addNumber( num1, num2 - 1 )

num1 = int(input('Number1-->'))
num2 = int(input('Number2-->'))
if num1 > num2 :
    num1, num2 = num2, num1
print(addNumber(num1, num2))

Self10-02.py

재귀로 구구단 가로 출력을 직접 구현합니다

def gugu(dan, num) :

    print("%dx%d=%2d" % (dan, num, dan*num), end = '  ')
    if dan < 9:
        gugu(dan+1, num)

for num in range(1,10) :
    gugu(2, num)
    print()

Self10-02.py

Implements horizontal multiplication table using recursion yourself

def gugu(dan, num) :

    print("%dx%d=%2d" % (dan, num, dan*num), end = '  ')
    if dan < 9:
        gugu(dan+1, num)

for num in range(1,10) :
    gugu(2, num)
    print()

🧪 Ch10. 재귀 호출 — 실습 코드 / Lab Code: Recursion

📘 교재 예제 (Code)

📘 Textbook Examples (Code)

📗 응용 예제 (Ex)

📗 Applied Examples (Ex)

📙 자가 실습 (Self)

📙 Self Practice (Self)