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Fix DateToDay #1126

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sharansukesh1003 wants to merge 10 commits into TheAlgorithms:master from sharansukesh1003:master
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59 changes: 19 additions & 40 deletions Conversions/DateToDay.js
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,59 +4,38 @@
The DateToDay method takes a date in string format and
returns the name of a day. The approach behind this method
is very simple, we first take a string date and check
whether their date is valid or not, if the date is valid
then we do this But apply the algorithm shown below. The
algorithm shown below gives us the number of the day and
finally converts it to the name of the day.

Algorithm & Explanation : https://cs.uwaterloo.ca/~alopez-o/math-faq/node73.html
whether their date is valid or not, if the date is not valid
then we return a type error, else we apply Zeller's congruence.
Algorithm & Explanation : https://www.geeksforgeeks.org/zellers-congruence-find-day-date/
*/

// March is taken as the first month of the year.
const calcMonthList = {
1: 11,
2: 12,
3: 1,
4: 2,
5: 3,
6: 4,
7: 5,
8: 6,
9: 7,
10: 8,
11: 9,
12: 10
}

// show the week day in a number : Sunday - Saturday => 0 - 6
const daysNameList = { // weeks-day
0: 'Sunday',
1: 'Monday',
2: 'Tuesday',
3: 'Wednesday',
4: 'Thursday',
5: 'Friday',
6: 'Saturday'
}

// days in a week : Sunday - Saturday => 0 - 6
const daysNameList = [
'Sunday',
'Monday',
'Tuesday',
'Wednesday',
'Thursday',
'Friday',
'Saturday'
]
const DateToDay = (date) => {
// firstly, check that input is a string or not.
if (typeof date !== 'string') {
return new TypeError('Argument is not a string.')
}
// extract the date
const [day, month, year] = date.split('/').map((x) => Number(x))
let [day, month, year] = date.split('/').map((x) => Number(x))
// check the data are valid or not.
if (day < 0 || day > 31 || month > 12 || month < 0) {
return new TypeError('Date is not valid.')
}
// divide year to century and yearDigit value.
const yearDigit = (year % 100)
// count Jan & Feb as months 13 & 14 of the previous year
if (month < 3) { year--; month += 12 }
const century = Math.floor(year / 100)
// Apply the algorithm shown above
const weekDay = Math.abs((day + Math.floor((2.6 * calcMonthList[month]) - 0.2) - (2 * century) + yearDigit + Math.floor(yearDigit / 4) + Math.floor(century / 4)) % 7)
// return the weekDay name.
return daysNameList[weekDay]
year %= 100
const weekDay = (year + Math.floor(year / 4) + Math.floor(century / 4) - 2 * century + Math.floor((26 * (month + 1)) / 10) + day - 1)
return daysNameList[(weekDay + 7) % 7]
}

// Example : DateToDay("18/12/2020") => Friday
Expand Down
4 changes: 2 additions & 2 deletions Conversions/test/DateToDay.test.js
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ import { DateToDay } from '../DateToDay'

test('The date 18/02/2001 is Monday', () => {
const res = DateToDay('18/02/2001')
expect(res).toBe('Monday')
expect(res).toBe('Sunday')
})

test('The date 18/12/2020 is Friday', () => {
Expand All @@ -16,5 +16,5 @@ test('The date 12/12/2012 is Wednesday', () => {
})
test('The date 01/01/2001 is Friday', () => {
const res = DateToDay('01/01/2001')
expect(res).toBe('Friday')
expect(res).toBe('Monday')
})

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