# HackerRank Prime Dates problem solution

In this HackerRank Prime Dates problem solution, the task is to debug the existing code to successfully execute all provided test files.

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.

## Problem solution in Python.

```def updateLeapYear(year):
if year % 400 == 0:
month[2] = 29
elif year % 100 == 0:
month[2] = 28
elif year % 4 == 0:
month[2] = 29
else:
month[2] = 28

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

while(True):
x = d1
x = x * 100 + m1
x = x * 10000 + y1
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
m1 = 1
return result;
```

## Problem solution in Java.

```import java.util.*;
import java.lang.*;
import java.io.*;
import java.math.*;

public class Main {

public static int month[];

public static void main (String[] args) throws java.lang.Exception {
Scanner in  = new Scanner(System.in);

month = new int[15];

String s = in.nextLine();

StringTokenizer str = new StringTokenizer(s, "- ");

int d1 = Integer.parseInt(str.nextToken());
int m1 = Integer.parseInt(str.nextToken());
int y1 = Integer.parseInt(str.nextToken());
int d2 = Integer.parseInt(str.nextToken());
int m2 = Integer.parseInt(str.nextToken());
int y2 = Integer.parseInt(str.nextToken());

int result = findPrimeDates(d1, m1, y1, d2, m2, y2);
System.out.println(result);
}

public static void updateLeapYear(int year) {
if(year % 400 == 0) {
month[2] = 29;
} else if(year % 100 == 0) {
month[2] = 28;
} else if(year % 4 == 0) {
month[2] = 29;
} else {
month[2] = 28;
}
}

public static void 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;
}

public static int findPrimeDates(int d1, int m1, int y1, int d2, int m2, int y2) {
storeMonth();

int result = 0;

while(true) {
int x = d1;
x = x * 100 + m1;
x = x * 10000 + y1;
if(x % 4 == 0 || x % 7 == 0) {
result = result + 1;
}
if(d1 == d2 && m1 == m2 && y1 == y2) {
break;
}
updateLeapYear(y1);
d1 = d1 + 1;
if(d1 > month[m1]) {
m1 = m1 + 1;
d1 = 1;
if(m1 > 12) {
y1 =  y1 + 1;
m1 = 1;
}
}
}
return result;
}
}
```

## Problem solution in C++.

```void updateLeapYear(int year) {
if(year % 400 == 0) {
month[2] = 29;
} else if(year % 100 == 0) {
month[2] = 28;
} else if(year % 4 == 0) {
month[2] = 29;
} else {
month[2] = 28;
}
}

void 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;
}

int findLuckyDates(int d1, int m1, int y1, int d2, int m2, int y2) {
storeMonth();

int result = 0;

while(true) {
int x = d1;
x = x * 100 + m1;
x = x * 10000 + y1;
if(x % 4 == 0 || x % 7 == 0) {
result = result + 1;
}
if(d1 == d2 && m1 == m2 && y1 == y2) {
break;
}
updateLeapYear(y1);
d1 = d1 + 1;
if(d1 > month[m1]) {
m1 = m1 + 1;
d1 = 1;
if(m1 > 12) {
y1 =  y1 + 1;
m1 = 1;
}
}
}
return result;
}
```