Given an array **arr[]**, the task is to count the number of pairs formed by consecutive elements in which both of the elements in a pair are same.

**Examples:**

Input:arr[] = {1, 2, 2, 3, 4, 4, 5, 5, 5, 5}Output:5

(1, 2), (4, 5), (6, 7), (7, 8) and (8, 9) are the valid index pairs

where consecutive elements are equal.

Input:arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}Output:0

No two consecutive elements in the given array are equal.

**Approach:** Initialize **count = 0** and traverse the array from **arr[0]** to **arr[n – 2]**. If the current element is equal to the next element in the array then increment the **count**. Print the **count** in the end.

Below is the implementation of the above approach:

## C++

`// C++ implementation of the approach` `#include <iostream>` `using` `namespace` `std;` ` ` `// Function to return the count of consecutive` `// elements in the array which are equal` `int` `countCon(` `int` `ar[], ` `int` `n)` `{` ` ` `int` `cnt = 0;` ` ` ` ` `for` `(` `int` `i = 0; i < n - 1; i++) {` ` ` ` ` `// If consecutive elements are same` ` ` `if` `(ar[i] == ar[i + 1])` ` ` `cnt++;` ` ` `}` ` ` `return` `cnt;` `}` ` ` `// Driver code` `int` `main()` `{` ` ` `int` `ar[] = { 1, 2, 2, 3, 4, 4, 5, 5, 5, 5 };` ` ` `int` `n = ` `sizeof` `(ar) / ` `sizeof` `(ar[0]);` ` ` `cout << countCon(ar, n);` ` ` ` ` `return` `0;` `}` |

## Java

`// Java implementation of the approach ` `public` `class` `GfG` `{` ` ` ` ` `// Function to return the count of consecutive ` ` ` `// elements in the array which are equal ` ` ` `static` `int` `countCon(` `int` `ar[], ` `int` `n) ` ` ` `{ ` ` ` `int` `cnt = ` `0` `; ` ` ` ` ` `for` `(` `int` `i = ` `0` `; i < n - ` `1` `; i++) ` ` ` `{ ` ` ` ` ` `// If consecutive elements are same ` ` ` `if` `(ar[i] == ar[i + ` `1` `]) ` ` ` `cnt++; ` ` ` `} ` ` ` `return` `cnt; ` ` ` `} ` ` ` ` ` `// Driver Code` ` ` `public` `static` `void` `main(String []args){` ` ` ` ` `int` `ar[] = { ` `1` `, ` `2` `, ` `2` `, ` `3` `, ` `4` `, ` `4` `, ` `5` `, ` `5` `, ` `5` `, ` `5` `}; ` ` ` `int` `n = ar.length; ` ` ` `System.out.println(countCon(ar, n));` ` ` `}` `}` ` ` `// This code is contributed by Rituraj Jain` |

## Python3

`# Python3 implementation of the approach` ` ` `# Function to return the count of consecutive` `# elements in the array which are equal` `def` `countCon(ar, n):` ` ` `cnt ` `=` `0` ` ` ` ` `for` `i ` `in` `range` `(n ` `-` `1` `):` ` ` ` ` `# If consecutive elements are same` ` ` `if` `(ar[i] ` `=` `=` `ar[i ` `+` `1` `]):` ` ` `cnt ` `+` `=` `1` ` ` ` ` `return` `cnt` ` ` `# Driver code` `ar ` `=` `[` `1` `, ` `2` `, ` `2` `, ` `3` `, ` `4` `,` ` ` `4` `, ` `5` `, ` `5` `, ` `5` `, ` `5` `]` `n ` `=` `len` `(ar)` `print` `(countCon(ar, n))` ` ` `# This code is contributed by mohit kumar` |

## C#

`// C# implementation of the approach ` `using` `System;` ` ` `class` `GfG` `{` ` ` ` ` `// Function to return the count of consecutive ` ` ` `// elements in the array which are equal ` ` ` `static` `int` `countCon(` `int` `[] ar, ` `int` `n) ` ` ` `{ ` ` ` `int` `cnt = 0; ` ` ` ` ` `for` `(` `int` `i = 0; i < n - 1; i++) ` ` ` `{ ` ` ` ` ` `// If consecutive elements are same ` ` ` `if` `(ar[i] == ar[i + 1]) ` ` ` `cnt++; ` ` ` `} ` ` ` `return` `cnt; ` ` ` `} ` ` ` ` ` `// Driver Code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` ` ` `int` `[] ar = { 1, 2, 2, 3, 4, 4, 5, 5, 5, 5 }; ` ` ` `int` `n = ar.Length; ` ` ` `Console.WriteLine(countCon(ar, n));` ` ` `}` `}` ` ` `// This code is contributed by Code_Mech.` |

## PHP

`<?php` `// PHP implementation of the approach` ` ` `// Function to return the count of consecutive` `// elements in the array which are equal` `function` `countCon(` `$ar` `, ` `$n` `)` `{` ` ` `$cnt` `= 0;` ` ` ` ` `for` `(` `$i` `= 0; ` `$i` `< ` `$n` `- 1; ` `$i` `++)` ` ` `{` ` ` ` ` `// If consecutive elements are same` ` ` `if` `(` `$ar` `[` `$i` `] == ` `$ar` `[` `$i` `+ 1])` ` ` `$cnt` `++;` ` ` `}` ` ` `return` `$cnt` `;` `}` ` ` `// Driver code` `$ar` `= ` `array` `(1, 2, 2, 3, 4, 4, 5, 5, 5, 5);` `$n` `= sizeof(` `$ar` `);` `echo` `countCon(` `$ar` `, ` `$n` `);` ` ` `// This code is contributed` `// by Akanksha Rai` `?>` |

**Output:**

5

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