# Count ways to spell a number with repeated digits

Given a string that contains digits of a number. The number may contain many same continuous digits in it. The task is to count number of ways to spell the number.
For example, consider 8884441100, one can spell it simply as triple eight triple four double two and double zero. One can also spell as double eight, eight, four, double four, two, two, double zero.

Examples :

```Input :  num = 100
Output : 2
The number 100 has only 2 possibilities,
1) one zero zero
2) one double zero.

Input : num = 11112
Output: 8
1 1 1 1 2, 11 1 1 2, 1 1 11 2, 1 11 1 2
11 11 2, 1 111 2, 111 1 2, 1111 2

Input : num = 8884441100
Output: 64

Input : num = 12345
Output: 1

Input : num = 11111
Output: 16
```

## Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

This is a simple problem of permutation and combination. If we take example test case given in the question, 11112. The answer depends on the number of possible combinations of 1111. The number of combinations of “1111” is 2^3 = 8. As our combinations will depend on whether we choose a particular 1 and for “2” there will be only one possibility 2^0 = 1, so answer for “11112” will be 8*1 = 8.
So, the approach is to count the particular continuous digit in string and multiply 2^(count-1) with previous result.

## C++

 `// C++ program to count number of ways we ` `// can spell a number ` `#include ` `using` `namespace` `std; ` `typedef` `long` `long` `int` `ll; ` ` `  `// Function to calculate all possible spells of ` `// a number with repeated digits ` `// num --> string which is favourite number ` `ll spellsCount(string num) ` `{ ` `    ``int` `n = num.length(); ` ` `  `    ``// final count of total possible spells ` `    ``ll result = 1; ` ` `  `    ``// iterate through complete number ` `    ``for` `(``int` `i=0; i

## Java

 `// Java program to count number of ways we ` `// can spell a number ` `class` `GFG { ` `     `  `    ``// Function to calculate all possible  ` `    ``// spells of a number with repeated digits ` `    ``// num --> string which is favourite number ` `    ``static` `long` `spellsCount(String num) ` `    ``{ ` `         `  `        ``int` `n = num.length(); ` ` `  `        ``// final count of total possible spells ` `        ``long` `result = ``1``; ` ` `  `        ``// iterate through complete number ` `        ``for` `(``int` `i = ``0``; i < n; i++) { ` `             `  `            ``// count contiguous frequency of  ` `            ``// particular digit num[i] ` `            ``int` `count = ``1``; ` `             `  `            ``while` `(i < n - ``1` `&& num.charAt(i + ``1``)  ` `                               ``== num.charAt(i)) { ` `                                     `  `                ``count++; ` `                ``i++; ` `            ``} ` ` `  `            ``// Compute 2^(count-1) and multiply  ` `            ``// with result ` `            ``result = result *  ` `                     ``(``long``)Math.pow(``2``, count - ``1``); ` `        ``} ` `        ``return` `result; ` `    ``} ` ` `  `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` ` `  `        ``String num = ``"11112"``; ` ` `  `        ``System.out.print(spellsCount(num)); ` `    ``} ` `} ` ` `  `// This code is contributed by Anant Agarwal. `

## Python3

 `# Python3 program to count number of ` `# ways we can spell a number ` ` `  `# Function to calculate all possible  ` `# spells of a number with repeated  ` `# digits num --> string which is  ` `# favourite number ` `def` `spellsCount(num): ` ` `  `    ``n ``=` `len``(num); ` ` `  `    ``# final count of total ` `    ``# possible spells ` `    ``result ``=` `1``; ` ` `  `    ``# iterate through complete ` `    ``# number ` `    ``i ``=` `0``; ` `    ``while``(i

## C#

 `// C# program to count number of ways we ` `// can spell a number ` `using` `System; ` ` `  `class` `GFG { ` `     `  `    ``// Function to calculate all possible  ` `    ``// spells of a number with repeated  ` `    ``// digits num --> string which is ` `    ``// favourite number ` `    ``static` `long` `spellsCount(String num) ` `    ``{ ` `         `  `        ``int` `n = num.Length; ` ` `  `        ``// final count of total possible ` `        ``// spells ` `        ``long` `result = 1; ` ` `  `        ``// iterate through complete number ` `        ``for` `(``int` `i = 0; i < n; i++) ` `        ``{ ` `             `  `            ``// count contiguous frequency of  ` `            ``// particular digit num[i] ` `            ``int` `count = 1; ` `             `  `            ``while` `(i < n - 1 && num[i + 1]  ` `                                ``== num[i]) ` `            ``{ ` `                ``count++; ` `                ``i++; ` `            ``} ` ` `  `            ``// Compute 2^(count-1) and multiply  ` `            ``// with result ` `            ``result = result *  ` `                    ``(``long``)Math.Pow(2, count - 1); ` `        ``} ` `         `  `        ``return` `result; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main() ` `    ``{ ` ` `  `        ``String num = ``"11112"``; ` ` `  `        ``Console.Write(spellsCount(num)); ` `    ``} ` `} ` ` `  `// This code is contributed by nitin mittal. `

## PHP

 ` string ` `// which is favourite number ` `function` `spellsCount(``\$num``) ` `{ ` `    ``\$n` `= ``strlen``(``\$num``); ` ` `  `    ``// final count of total ` `    ``// possible spells ` `    ``\$result` `= 1; ` ` `  `    ``// iterate through  ` `    ``// complete number ` `    ``for` `(``\$i` `= 0; ``\$i` `< ``\$n``; ``\$i``++) ` `    ``{ ` `    ``// count contiguous frequency  ` `    ``// of particular digit num[i] ` `    ``\$count` `= 1; ` `    ``while` `(``\$i` `< ``\$n` `- 1 &&  ` `           ``\$num``[``\$i` `+ 1] == ``\$num``[``\$i``]) ` `    ``{ ` `        ``\$count``++; ` `        ``\$i``++; ` `    ``} ` ` `  `    ``// Compute 2^(count-1) and ` `    ``// multiply with result  ` `    ``\$result` `= ``\$result` `*  ` `              ``pow(2, ``\$count` `- 1); ` `    ``} ` `    ``return` `\$result``; ` `} ` ` `  `// Driver Code ` `\$num` `= ``"11112"``; ` `echo` `spellsCount(``\$num``); ` ` `  `// This code is contributed ` `// by nitin mittal.  ` `?> `

Output :

```8
```

If you have another approach to solve this problem then please share.

This article is contributed by Shashank Mishra ( Gullu ). If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.