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재귀함수
(a)
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def mult(i,j):
print(i,"*",j,"=",i*j)
def right(i,j,n):
if j < n:
mult(i,j)
right(i,j+1,n)
right(2,1,10)
2 * 1 = 2 2 * 2 = 4 2 * 3 = 6 2 * 4 = 8 2 * 5 = 10 2 * 6 = 12 2 * 7 = 14 2 * 8 = 16 2 * 9 = 18
(b)
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def mult(i,j):
print(i,"*",j,"=",i*j)
def right(i,j,n):
if j < n:
mult(i,j)
right(i,j+1,n)
def left(i,m,n):
if i < m:
right(i,1,n)
left(i+1,m,n)
left(2,5,3)
2 * 1 = 2 2 * 2 = 4 3 * 1 = 3 3 * 2 = 6 4 * 1 = 4 4 * 2 = 8
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left(2,5,3) -> rigth(2,1,3) -> mult(2,1)
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| right(2,2,3) -> mult(2,2)
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| right(2,3,3)
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left(3,5,3) -> rigth(3,1,3) -> mult(3,1)
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| right(3,2,3) -> mult(3,2)
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| right(3,3,3)
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left(4,5,3) -> rigth(4,1,3) -> mult(4,1)
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| right(4,2,3) -> mult(4,2)
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| right(4,3,3)
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left(5,5,3)
nested for loop (for 두개)로 만들 수 있음
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문자열과 리스트의 관계 예제
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s = 'This is right justified'
def mysplit(s):
lst = []
tmp = ''
for c in s:
if c != ' ':
tmp = tmp + c
else:
lst.append(tmp)
tmp = ''
if tmp != '':
lst.append(tmp)
tmp = ''
return lst
print(mysplit(s))
[‘This’, ‘is’, ‘right’, ‘justified’]
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파이썬의 기본 함수들 예제
(a)
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x = [1,2,3]
print(len(x))
x.append(4)
print(len(x))
3 4
(b)
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print('hello'.upper())
HELLO
(c)
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print('{0}'.format(3 + 4))
7
(d)
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print('{x}'.format(x=3+4))
7
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파이썬으로 Vector 클래스를 정의한 예제
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class Vector:
def __init__(self,lst):
self.vec = lst
def __repr__(self):
return "Vector({0})".format(self.vec)
def __add__(self,other):
return Vector([self.vec[i] + other.vec[i] for i in range(len(self.vec))])
x = Vector([1,2,3])
print(x + x)
Vector([2, 4, 6])
init은 Vector가 실행될때 가장 먼저 실행되는것
