Wants to know logic how to convert it into code (C lan)

Question

Mr. Sam was born on XX-YY-ZZZZ which happened to be a Saturday. If he died on AA-BB-CCCC, how many birthdays would he celebrate that fall on a Monday?

Assume, the year which is divisible by 4 are leap years and February has 29 days in a leap year. Also, rest of the calendar months have same days as in original calendar.

For example If Sam was born on 28-05-2022 and died on 28-05-2023 then number of birthdays he would have celebrated that fall on a Monday is 0 .

Answer 1

The specification is very unclear.

1) What kind of calendar is it referring to? Gregorian? Julian?

2) Whichever calendar, the day of birth determines the day of week; there is no guarantee that it will be Saturday.

3) How is birthday celebrated if he is born on February 29?

4) Does he celebrate birthday if he happens to die the same day?

Anyway, below is a solution for some arbitrary disambiguation of the specifications.

// Return true if the first date is before the second date

bool isBefore(int day1, int month1,

int day2, int month2)

{

if (month1 < month2) return true;

if (month1 > month2) return false;

return (day1 < day2);

}

// Return number of days in give year according to Gregorian calendar.

// However, the problem statement may be refering to the Julian calendar.

// If so, you need to change this code.

int numDays(int year)

{

if (year % 400 == 0) return 366;

if (year % 100 == 0) return 365;

if (year % 4 == 0) return 366;

return 365;

}

// If the given date falls before February 29 then any insertion of leap day

// would be determined by the current year.

// Otherwise it would be determined by the next year.

int numDaysToNextBirthday(int day, int month, int year)

{

if (isBefore(day, month, 2, 29)) return numDays(year);

else return numDays(year+1);

}

////////////////////////////////////////////////////////////////////////

// MAIN CODE

// Days of the week are represented (arbitrarily) as

// 0: Sunday

// 1: Monday

// ...

// 6: Saturday

int dayOfWeek = 6; // Given that born on Saturday

int numBirthdaysOnMonday = 0; // the final result to be calculated

// Set endYear to the last year when birthday will be selebrated.

// If he dies on his birthday, assume that he does not selebrate his birthday

int endYear = isBefore(XX, YY, AA, BB) ? CCCC : CCCC-1;

int year; // iterates over each year since birth

for (year = ZZZZ; // start with the year born

year < endYear; // end with the year before the last birthday

year++) {

// Calculate the day of the week on which the next birthday will fall

dayOfWeek = (dayOfWeek + numDaysToNextBirthday(XX, YY, year)) % 7;

// If it is Monday, count it

if (dayOfWeek == 1) numBirthdaysOnMonday++;

}