Prime Dates

HackerRank 問題: Prime Dates
Categories:
Tags:

Question

Given two dates each in the format dd-mm-yyyy, you have to find the number of lucky dates between them (inclusive). To see if a date is lucky,

  • Firstly, sequentially concatinate the date, month and year, into a new integer x erasing the leading zeroes.
  • Now if x is divisible by either 4 or 7, then we call the date a lucky date.

For example, let’s take the date “02-08-2024”. After concatinating the day, month and year, we get x = 2082024. As x is divisible by 4 so the date “02-08-2024” is called a lucky date.

Debug the given function findPrimeDates and/or other lines of code, to find the correct lucky dates from the given input.

Note: You can modify at most five lines in the given code and you cannot add or remove lines to the code.

HackerRank 問題: Prime Dates

Answer

import re
month = []

def updateLeapYear(year):
    if year % 400 == 0:
        # 1. leap year wrong, change 28 => 29
        month[2] = 29
    elif year % 100 == 0:
        # 2. leap year wrong, change 29 => 28
        month[2] = 28
    elif year % 4 == 0:
        month[2] = 29
    else:
        month[2] = 28

def storeMonth():
    month[1] = 31
    month[2] = 28
    month[3] = 31
    month[4] = 30
    month[5] = 31
    month[6] = 30
    month[7] = 31
    month[8] = 31
    month[9] = 30
    month[10] = 31
    month[11] = 30
    month[12] = 31

def findPrimeDates(d1, m1, y1, d2, m2, y2):
    storeMonth()
    result = 0

    while(True):
        x = d1
        x = x * 100 + m1
        # 3: 1000 -> 10000
        x = x * 10000 + y1
        # 4: condition wrong, change "and" to "or"
        if x % 4 == 0 or x % 7 == 0:
            result = result + 1
        if d1 == d2 and m1 == m2 and y1 == y2:
            break

        updateLeapYear(y1)

        d1 = d1 + 1

        if d1 > month[m1]:

            m1 = m1 + 1
            d1 = 1

            if m1 > 12:
                y1 = y1 + 1
                # 5: month reset
                m1 = 1

for i in range(1, 15):
    month.append(31)

line = input()
date = re.split('-| ', line)
d1 = int(date[0])
m1 = int(date[1])
y1 = int(date[2])
d2 = int(date[3])
m2 = int(date[4])
y2 = int(date[5])

result = findPrimeDates(d1, m1, y1, d2, m2, y2)
print(result)

Reference