순열 및 조합 (43165 타겟 넘버)

순열, 조합

from itertools import permutations, combinations, product, combinations_with_replacement

# (1) 순열(permutations)
a = list(permutations(['A', 'B', 'C'], 2))
print(a)    # nPr, [('A', 'B'), ('A', 'C'), ('B', 'A'), ('B', 'C'), ('C', 'A'), ('C', 'B')]

# (2) 조합(combinations)
a = list(combinations(['A','B','C'], 2))
print(a)    # nCr, [('A', 'B'), ('A', 'C'), ('B', 'C')]

# (3) 중복순열(product)
a = list(product(['A','B','C'], repeat=4))
print(a)    # nPr

# (4) 중복조합(combinations_with_replacement)
a = list(combinations_with_replacement(['A','B','C'], 2))
print(a)    # nHr

개수만 구하고자 할 때,

import math

math.perm(n, r)

math.comb(n, r)

math.factorial(n)

코테 문제

1. 타겟 넘버 (프로그래머스_level2)

(1) 중복순열

import copy
from itertools import product

def solution(numbers, target):
    arr = list(product([1,-1], repeat=len(numbers)))
    result = []
    for i in range(len(arr)):
        result.append(sum([x*y for x,y in zip(numbers, arr[i])]))

    return result.count(target)