Count pairs with given sum

Problem :

http://practice.geeksforgeeks.org/problems/count-pairs-with-given-sum/0

Solution :

Matrix Transpose

Given a 2D array A, your task is to convert all rows to columns and columns to rows.
Input:
First line contains 2 space separated integers, N - total rows, M - total columns.
Each of the next N lines will contain M space separated integers.
Output:
Print M lines each containing N space separated integers.
Constraints:
$1\le N\le 10$
$1\le M\le 10$
$0\le A\left[i\right]\left[j\right]\le 100$ where $1\le i\le N$ and $1\le j\le M$

$\mathrm{Solution}$

Count frequency of each element in array

Write a program to count the frequency of each element in array , as example if we have 
int a[10]={5, 10, 2, 5, 50, 5, 10, 1, 2, 2};
the output should be 
number     frequency
5          3
10         2
2          3
50         1
1          1