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;
}
