Plus Minus (Python 3)

• URL : https://www.hackerrank.com/challenges/plus-minus/problem

Given an array of integers, calculate the ratios of its elements that are positive, negative, and zero. Print the decimal value of each fraction on a new line with 6 places after the decimal.

• Note: This challenge introduces precision problems. The test cases are scaled to six decimal places, though answers with absolute error of up to 10^-4 are acceptable.

• Example

  • arr = [1,1,0,-1,-1]
  • There are n = 5 elements, two positive, two negative and one zero. Their ratios are 2/5 = 0.400000, 2/5 = 0.400000 and 1/5 = 0.200000. Results are printed as:

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0.400000
0.400000
0.200000

• Function Description
  • Complete the plusMinus function in the editor below.
  • plusMinus has the following parameter(s):
    • int arr[n]: an array of integers
• Print
  • Print the ratios of positive, negative and zero values in the array. Each value should be printed on a separate line with 6 digits after the decimal. The function should not return a value.
• Input Format
  • The first line contains an integer, n, the size of the array.
  • The second line contains n space-separated integers that describe arr[n].
• Constraints
  • 0 < n <= 100
  • -100 <= arr[i] <= 100
• Output Format
  • Print the following 3 lines, each to 6 decimals:
    1. proportion of positive values
    2. proportion of negative values
    3. proportion of zeros

문제풀이

• 주어진 arr에서 음수, 양수, 0을 확인하고 전체 갯수를 음수, 양수, 0의 갯수로 나눈 값을 출력하기
• for문을 돌면서 음수면 음수,양수면 양수 등 할수있으나, fillter 함수와 lambda 함수를 통해 양, 음, 0을 더 빠르게 확인.
• fillter 후에 list시키고 그 갯수(len)만큼 나누는 코드를 생성

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import math
import os
import random
import re
import sys

# Complete the plusMinus function below.
def plusMinus(arr):
    print(round(len(list(filter(lambda x : x > 0, arr))) / len(arr), 6))
    print(round(len(list(filter(lambda x : x < 0, arr))) / len(arr), 6))
    print(round(len(list(filter(lambda x : x == 0, arr))) / len(arr), 6))

if __name__ == '__main__':
    n = int(input())

    arr = list(map(int, input().rstrip().split()))

    plusMinus(arr)

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 -4 3 -9 0 4 1


0.5
0.5
0.5