🧪 Ch02. 알고리즘 시작 — 실습 코드 / Lab Code: Getting Started with Algorithms

Function definition and call: create and use an addition function

## Function Declarations ## 
def plus( v1, v2) :

	result = 0
	result = v1 + v2
	return result

## Global Variables ## 
hap = 0

## Main Code ## 
hap = plus(100, 200)
print("Result of plus(100,200) is %d" % hap)

Demonstrates the difference between local and global variables

## Function Declarations ## 
def func1():

	a = 10  # local variable
	print("Value of a in func1(): %d" % a)

def func2():

	print("Value of a in func2(): %d" % a)

## Global Variables ## 
a = 20  # global variable

## Main Code ## 
func1()
func2()

Uses the global keyword to modify a global variable inside a function

## Function Declarations ## 
def func1():

	global a  # a is global inside this function
	a = 10
	print("Value of a in func1(): %d" % a)

def func2():

	print("Value of a in func2(): %d" % a)

## Global Variables ## 
a = 20  # global variable

## Main Code ## 
func1()
func2()

Implements a function that returns multiple values via a list

## Function Declarations ## 
def multi(v1, v2):

	retList = []  # list to return
	res1 = v1 + v2
	res2 = v1 - v2
	retList.append(res1)
	retList.append(res2)
	return retList

## Global Variables ##
myList = []
hap, sub = 0, 0

## Main Code ##
myList = multi(100, 200)
hap = myList[0]
sub = myList[1]
print("Values returned by multi() ==> %d, %d" % (hap, sub))

Creates a 1D array and computes its sum

aa = []
for i in range(0, 4) :
	aa.append(0)

for i in range(0, 4) :
	aa[i] = int(input(  str(i+1) + "th number: " ))

hap = 0
for i in range(0, 4) :
	hap = hap + aa[i]

print(" Sum ==> %d " % hap)

Practices various list built-in methods (append, pop, sort, etc.)

myList = [30, 10, 20]
print("Current list: %s" % myList)

myList.append(40)
print("List after append(40): %s" % myList)

print("Value from pop(): %s" % myList.pop())
print("List after pop(): %s" % myList)

myList.sort()
print("List after sort(): %s" % myList)

myList.reverse()
print("List after reverse(): %s" % myList)

print("Index of 20: %d" % myList.index(20))

myList.insert(2, 222)
print("List after insert(2,222): %s" % myList)

myList.remove(222)
print("List after remove(222): %s" % myList)

myList.extend( [77 , 88, 77] )
print("List after extend([77,88,77]): %s" % myList)

print("Count of 77: %d" % myList.count(77))

Creates and populates a 2D list

list1 = [ ]
list2 = [ ]
value=1
for i in range(0, 3) :
	for k in range(0, 4) :
		list1.append(value)
		value += 1
	list2.append(list1)
	list1 = []

for i in range(0, 3) :
	for k in range(0, 4) :
		print("%3d" % list2[i][k], end = " ")
	print(" ")

Creates a dictionary and handles key-value pairs

singer = {}

singer['name'] = 'TWICE'
singer['members'] = 9
singer['debut'] = 'Survival Sixteen'
singer['hit_song'] = 'SIGNAL'

for k in singer.keys() :
    print('%s  -->  %s'  % (k, singer[k]))

Implements a random lotto number generator

import random

## Global Variables ##
totalLotto = []
lotto = []
pickNum = 0
count = 0

## Main Code ##
print("** Starting lotto number generation. **")
count = int(input('How many draws?'))

for _ in range(count) :
	 lotto = []
	 while True :
		  pickNum = random.randint(1, 45)
		  if pickNum not in lotto :
			   lotto.append(pickNum)
		  if len(lotto) >= 6 :
			   break
	 totalLotto.append(lotto)

for lotto in totalLotto :
	 lotto.sort()
	 print('Auto number--> ', end = ' ')
	 for i in range(0, 6) :
		  print("%2d" % lotto[i], end = ' ')
	 print()

Reads a text file and analyzes character frequency

## Global Variables ##
poet = '''
When you leave, sick of the sight of me, I will let you go without a word
I will gather azaleas from Yaksan, Yeongbyeon, and scatter them on your path
Step by step on the flowers before you, tread softly as you go
When you leave, sick of the sight of me, even in death I will not shed tears
 '''
countDic = {}

## Main Code ##
if __name__ == "__main__" :
	for ch in poet :
		if ch.isalpha() :
			if ch in countDic :
				countDic[ch] += 1
			else :
				countDic[ch] = 1

	print('Original', poet)
	print('-------------------------')
	print('Character frequency (4+ times)')
	print('-------------------------')
	for key in countDic :
		if countDic[key] >= 4 :
			print(key, '-->', countDic[key])

Writes a function returning arithmetic results as a list

## Function Declarations ##
def multi(v1, v2) :

    retList = []
    retList.append(v1 + v2)
    retList.append(v1 - v2)
    retList.append(v1 * v2)
    retList.append(v1 // v2)
    retList.append(v1 % v2)
    retList.append(v1 ** v2)
    return retList

## Global Variables ##
myList = []
hap, sub = 0, 0

## Main Code ##
myList = multi(100, 20)
print("Values returned by multi() ==> ", (myList))

Fills and prints a 2D list

list1 = []
list2 = []
value = 12
for i in range(0, 4) :
	for k in range(0, 3) :
		list1.append(value)
		value -= 1
	list2.append(list1)
	list1 = []

for i in range(0, 4) :
	for k in range(0, 3) :
		print("%3d" % list2[i][k], end = " ")
	print("")

hap = 0
for i in range(0, 4) :
	for k in range(0, 3) :
		hap += list2[i][k]

print("Array Sum ==>", hap)