# Find the count of M character words which have at least one character repeated

Given two integers **N** and **M**, the task is count the total words of **M** character length formed by the given **N** distinct characters such that the words have at least one character repeated more than once.

**Examples:**

Input:N = 3, M = 2

Output:3

Suppose the characters are {‘a’, ‘b’, ‘c’}

All 2 length words that can be formed with these characters

are “aa”, “ab”, “ac”, “ba”, “bb”, “bc”, “ca”, “cb” and “cc”.

Out of these words only “aa”, “bb” and “cc” have

at least one character repeated more than once.

Input:N = 10, M = 5

Output:69760

**Approach:**

Total number of M character words possible from N characters, **total = N ^{M}**.

Total number of M character words possible from N characters where no character repeats itself,

**noRepeat =**.

^{N}P_{M}So, total words where at least a single character appear more than once is

**total – noRepeat**i.e.

**N**.

^{M}–^{N}P_{M}Below is the implementation of the above approach:

## Java

`// Java implementation of the approach ` `class` `GFG { ` ` ` ` ` `// Function to return the ` ` ` `// factorial of a number ` ` ` `static` `int` `fact(` `int` `n) ` ` ` `{ ` ` ` `if` `(n <= ` `1` `) ` ` ` `return` `1` `; ` ` ` `return` `n * fact(n - ` `1` `); ` ` ` `} ` ` ` ` ` `// Function to return the value of nPr ` ` ` `static` `int` `nPr(` `int` `n, ` `int` `r) ` ` ` `{ ` ` ` `return` `fact(n) / fact(n - r); ` ` ` `} ` ` ` ` ` `// Function to return the total number of ` ` ` `// M length words which have at least a ` ` ` `// single character repeated more than once ` ` ` `static` `int` `countWords(` `int` `N, ` `int` `M) ` ` ` `{ ` ` ` `return` `(` `int` `)Math.pow(N, M) - nPr(N, M); ` ` ` `} ` ` ` ` ` `// Driver code ` ` ` `public` `static` `void` `main(String[] args) ` ` ` `{ ` ` ` `int` `N = ` `10` `, M = ` `5` `; ` ` ` `System.out.print(countWords(N, M)); ` ` ` `} ` `} ` |

*chevron_right*

*filter_none*

## C#

// C# implementation of the approach

using System;

class GFG

{

// Function to return the

// factorial of a number

static int fact(int n)

{

if (n <= 1)
return 1;
return n * fact(n - 1);
}
// Function to return the value of nPr
static int nPr(int n, int r)
{
return fact(n) / fact(n - r);
}
// Function to return the total number of
// M length words which have at least a
// single character repeated more than once
static int countWords(int N, int M)
{
return (int)Math.Pow(N, M) - nPr(N, M);
}
// Driver code
static public void Main ()
{
int N = 10, M = 5;
Console.Write(countWords(N, M));
}
}
// This code is contributed by ajit.
[tabbyending]

**Output:**

69760

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