Given two years Y1 and Y2 where 103 ≤ Y1 ≤ Y2 ≤ 106, the task is to find and print all the dates which are palindromes between the given years.
Examples:
Input: Y1 = 2001, Y2 = 2005
Output:
10022001
20022002
Input: Y1 = 5000, Y2 = 5010
Output:
10055001
20055002
30055003
01055010
Approach: Since the first four digits (i.e. the day and the month) have to be the reverse of the last four digits (the year) in order for the date to be a palindrome. So, every year will have at most one palindrome date. In order to find the dates, for every year reverse the year number and check whether the date formed is valid or not. If it is valid then print it.
Below is the implementation of the above approach:
// C++ implementation of the approach #include <bits/stdc++.h> using namespace std;
const int MAX_VALID_YR = 9999;
const int MIN_VALID_YR = 1800;
// Returns true if // given year is valid bool isLeap( int year)
{ // Return true if year
// is a multiple of 4 and
// not multiple of 100.
// OR year is multiple of 400.
return (((year % 4 == 0)
&& (year % 100 != 0))
|| (year % 400 == 0));
} // Returns true if given // year is valid or not. bool isValidDate( int d, int m, int y)
{ // If year, month and day
// are not in given range
if (y > MAX_VALID_YR || y < MIN_VALID_YR)
return false ;
if (m < 1 || m > 12)
return false ;
if (d < 1 || d > 31)
return false ;
// Handle February month
// with leap year
if (m == 2) {
if (isLeap(y))
return (d <= 29);
else
return (d <= 28);
}
// Months of April, June,
// Sept and Nov must have
// number of days less than
// or equal to 30.
if (m == 4 || m == 6 || m == 9 || m == 11)
return (d <= 30);
return true ;
} // Function to print the palindrome // dates between the given years void printPalindromeDates( int y1, int y2)
{ // For every year
for ( int year = y1; year <= y2; year++) {
// Current year as a string
string str = to_string(year);
// To store the reverse of year
string rev = str;
reverse(rev.begin(), rev.end());
// Get the day and the month
int day = stoi(rev.substr(0, 2));
int month = stoi(rev.substr(2, 2));
// If the current palindrome date is valid
if (isValidDate(day, month, year)) {
cout << rev << str << endl;
}
}
} // Driver code int main()
{ int y1 = 2001, y2 = 2005;
printPalindromeDates(y1, y2);
return 0;
} |
// Java implementation of the approach class GFG
{ static int MAX_VALID_YR = 9999 ;
static int MIN_VALID_YR = 1800 ;
// Returns true if // given year is valid static boolean isLeap( int year)
{ // Return true if year
// is a multiple of 4 and
// not multiple of 100.
// OR year is multiple of 400.
return (((year % 4 == 0 )
&& (year % 100 != 0 ))
|| (year % 400 == 0 ));
} // Returns true if given // year is valid or not. static boolean isValidDate( int d, int m, int y)
{ // If year, month and day
// are not in given range
if (y > MAX_VALID_YR || y < MIN_VALID_YR)
return false ;
if (m < 1 || m > 12 )
return false ;
if (d < 1 || d > 31 )
return false ;
// Handle February month
// with leap year
if (m == 2 )
{
if (isLeap(y))
return (d <= 29 );
else
return (d <= 28 );
}
// Months of April, June,
// Sept and Nov must have
// number of days less than
// or equal to 30.
if (m == 4 || m == 6 || m == 9 || m == 11 )
return (d <= 30 );
return true ;
} // Function to print the palindrome // dates between the given years static void printPalindromeDates( int y1, int y2)
{ // For every year
for ( int year = y1; year <= y2; year++)
{
// Current year as a String
String str = String.valueOf(year);
// To store the reverse of year
String rev = str;
rev = reverse(rev);
// Get the day and the month
int day = Integer.parseInt(rev.substring( 0 , 2 ));
int month = Integer.parseInt(rev.substring( 2 , 2 + 2 ));
// If the current palindrome date is valid
if (isValidDate(day, month, year))
{
System.out.print(rev + str + "\n" );
}
}
} static String reverse(String input)
{ char [] a = input.toCharArray();
int l, r = a.length - 1 ;
for (l = 0 ; l < r; l++, r--)
{
char temp = a[l];
a[l] = a[r];
a[r] = temp;
}
return String.valueOf(a);
}
// Driver code public static void main(String[] args)
{ int y1 = 2001 , y2 = 2005 ;
printPalindromeDates(y1, y2);
} } // This code is contributed by PrinciRaj1992 |
# Python 3 implementation of the approach MAX_VALID_YR = 9999
MIN_VALID_YR = 1800
# Returns true if given year is valid def isLeap(year):
# Return true if year
# is a multiple of 4 and
# not multiple of 100.
# OR year is multiple of 400.
return (((year % 4 = = 0 ) and
(year % 100 ! = 0 )) or
(year % 400 = = 0 ))
# Returns true if given # year is valid or not. def isValidDate(d, m, y):
# If year, month and day
# are not in given range
if (y > MAX_VALID_YR or y < MIN_VALID_YR):
return False
if (m < 1 or m > 12 ):
return False
if (d < 1 or d > 31 ):
return False
# Handle February month
# with leap year
if (m = = 2 ):
if (isLeap(y)):
return (d < = 29 )
else :
return (d < = 28 )
# Months of April, June,
# Sept and Nov must have
# number of days less than
# or equal to 30.
if (m = = 4 or m = = 6 or
m = = 9 or m = = 11 ):
return (d < = 30 )
return True
# Function to print the palindrome # dates between the given years def printPalindromeDates(y1, y2):
# For every year
for year in range (y1, y2 + 1 , 1 ):
# Current year as a string
str1 = str (year)
# To store the reverse of year
rev = str1
rev = rev[:: - 1 ]
# Get the day and the month
day = int (rev[ 0 : 2 ])
month = int (rev[ 2 : 4 ])
# If the current palindrome date is valid
rev + = str1
if (isValidDate(day, month, year)):
print (rev)
# Driver code if __name__ = = '__main__' :
y1 = 2001
y2 = 2005
printPalindromeDates(y1, y2)
# This code is contributed by Surendra_Gangwar |
// C# implementation of the approach using System;
class GFG
{ static int MAX_VALID_YR = 9999;
static int MIN_VALID_YR = 1800;
// Returns true if // given year is valid static bool isLeap( int year)
{ // Return true if year
// is a multiple of 4 and
// not multiple of 100.
// OR year is multiple of 400.
return (((year % 4 == 0) &&
(year % 100 != 0)) ||
(year % 400 == 0));
} // Returns true if given // year is valid or not. static bool isValidDate( int d, int m, int y)
{ // If year, month and day
// are not in given range
if (y > MAX_VALID_YR || y < MIN_VALID_YR)
return false ;
if (m < 1 || m > 12)
return false ;
if (d < 1 || d > 31)
return false ;
// Handle February month
// with leap year
if (m == 2)
{
if (isLeap(y))
return (d <= 29);
else
return (d <= 28);
}
// Months of April, June,
// Sept and Nov must have
// number of days less than
// or equal to 30.
if (m == 4 || m == 6 || m == 9 || m == 11)
return (d <= 30);
return true ;
} // Function to print the palindrome // dates between the given years static void printPalindromeDates( int y1, int y2)
{ // For every year
for ( int year = y1; year <= y2; year++)
{
// Current year as a String
String str = String.Join( "" , year);
// To store the reverse of year
String rev = str;
rev = reverse(rev);
// Get the day and the month
int day = Int32.Parse(rev.Substring(0, 2));
int month = Int32.Parse(rev.Substring(2, 2));
// If the current palindrome date is valid
if (isValidDate(day, month, year))
{
Console.Write(rev + str + "\n" );
}
}
} static String reverse(String input)
{ char [] a = input.ToCharArray();
int l, r = a.Length - 1;
for (l = 0; l < r; l++, r--)
{
char temp = a[l];
a[l] = a[r];
a[r] = temp;
}
return String.Join( "" , a);
} // Driver code public static void Main(String[] args)
{ int y1 = 2001, y2 = 2005;
printPalindromeDates(y1, y2);
} } // This code is contributed by 29AjayKumar |
// JS implementation of the approach let MAX_VALID_YR = 9999; let MIN_VALID_YR = 1800; // Returns true if // given year is valid function isLeap(year)
{ // Return true if year
// is a multiple of 4 and
// not multiple of 100.
// OR year is multiple of 400.
return (((year % 4 == 0)
&& (year % 100 != 0))
|| (year % 400 == 0));
} // Returns true if given // year is valid or not. function isValidDate(d, m, y)
{ // If year, month and day
// are not in given range
if (y > MAX_VALID_YR || y < MIN_VALID_YR)
return false ;
if (m < 1 || m > 12)
return false ;
if (d < 1 || d > 31)
return false ;
// Handle February month
// with leap year
if (m == 2) {
if (isLeap(y))
return (d <= 29);
else
return (d <= 28);
}
// Months of April, June,
// Sept and Nov must have
// number of days less than
// or equal to 30.
if (m == 4 || m == 6 || m == 9 || m == 11)
return (d <= 30);
return true ;
} // Function to print the palindrome // dates between the given years function printPalindromeDates(y1, y2)
{ // For every year
for (let year = y1; year <= y2; year++) {
// Current year as a string
let str = "" + year;
// To store the reverse of year
let rev = str.split( "" ).reverse().join( "" );
// Get the day and the month
let day = parseInt(rev.substr(0, 2));
let month = parseInt(rev.substr(2, 2));
// If the current palindrome date is valid
if (isValidDate(day, month, year)) {
console.log(rev + str);
}
}
} // Driver code let y1 = 2001, y2 = 2005; printPalindromeDates(y1, y2); // This code is contributed by phasing17 |
10022001 20022002
Time Complexity: O(y2 – y1)
Auxiliary Space: O(1)