# Print all palindrome dates between the given years

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++

 `// C++ implementation of the approach ` `#include ` `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 pf 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

 `// 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 pf 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

 `# 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 pf 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#

 `// 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 pf 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 `

Output:

```10022001
20022002
```

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