[프로그래머스] 교점에 별 만들기

 

출처: 프로그래머스 코딩 테스트 연습, https://programmers.co.kr/learn/challenges

 

 

 

 

** Python

 

하는 중...!

교점까지는 접근해봤음..!

 

 

def solution(line):
    visited = []
    crossed = set()
    answer = []
    for i, l1 in enumerate(line):
        for j, l2 in enumerate(line):
            if (i, j) in visited or (j, i) in visited:
                continue
            a, b, e = l1
            c, d, f = l2
            if a*d - b*c != 0:
                x = round((b*f - e*d)/(a*d - b*c), 2)
                y = round((e*c - a*f)/(a*d - b*c), 2)
                if x.is_integer() and y.is_integer(): crossed.add((x, y))
    print(crossed)
    if len(crossed) == 1: return ["*"]
    return answer

 

x.is_integer() 랑 y.is_integer 에서 문제가 있었던 것 같다.

 

x == int(x)

y == int(y)로 바꾸니까 됐음

 

def solution(line):
    visited = []
    crossed = set()
    answer = []
    
    for i, l1 in enumerate(line):
        for j, l2 in enumerate(line):
            if (i, j) in visited or (j, i) in visited:
                continue
            a, b, e = l1
            c, d, f = l2
            if a * d - b * c != 0:
                x = (b*f - e*d)/(a*d - b*c)
                y = (e*c - a*f)/(a*d - b*c)
                if x == int(x) and y == int(y):
                    crossed.add((int(x), int(y)))
    xs = [c[0] for c in crossed]
    x_min = min(xs)
    x_max = max(xs)
    
    ys = [c[1] for c in crossed]
    y_min = min(ys)
    y_max = max(ys)
    
    answer = ['.' * (x_max - x_min + 1)] * (y_max - y_min + 1)
    for c in crossed:
        x, y = c
        answer[y_max - y] = answer[y_max - y][:x - x_min] + '*' + answer[y_max - y][x - x_min + 1:]
    return [''.join(ans) for ans in answer]

 

 

 

참고했던 식

from itertools import combinations

# 두 직선의 모든 좌표가 정수인 교점 구하기
def intersection_point(line1, line2):
    a,b,e = line1
    c,d,f = line2
    if a*d == b*c:
        return None
    x = (b*f-e*d)/(a*d-b*c)
    y = (e*c-a*f)/(a*d-b*c)
    if x == int(x) and y == int(y):
        return (int(x),int(y))
    
def solution(line):
    N = len(line)
    # 두 직선씩 짝지어 교점 구하기 
    combs = list(combinations(line,2))
    points = set()
    for comb in combs:
        point = intersection_point(comb[0], comb[1])
        if point:
            points.add(point)
            
    # 교점의 x좌표들 
    xs = [p[0] for p in points]
    x_min = min(xs)
    x_max = max(xs)
    
    # 교점의 y좌표들
    ys = [p[1] for p in points]
    y_min = min(ys)
    y_max = max(ys)
    
    # 모두 . 으로 초기화 
    answer = ['.' * (x_max-x_min+1)] * (y_max-y_min+1)
    # 각 좌표마다 * 그리기 
    for point in points:
        x,y = point
        answer[y_max-y] = answer[y_max-y][:x-x_min] + '*' + answer[y_max-y][x-x_min+1:]
    return [''.join(ans) for ans in answer]

참고: https://codlingual.tistory.com/252