Lv 1 두 개 뽑아서 더하기

def solution(numbers):
    answer = []
    n = len(numbers)
    for i in range(n):
        for j in range(i+1, n):
            answer.append((numbers[i]+numbers[j]))

    answer = list(set(answer))
    answer.sort()
    return answer

참고 https://m31phy.tistory.com/130