Determining the most used value in an array

I am needing to write an application that determines the value that comes up most often in an array in C++ and its position in the array.

For example, if I have an array A where

A[0] = 3    A[1] = 4    A[2] =  3
A[3] = 2    A[4] = 3    A[5] = -1
A[6] = 3    A[7] = 3

I must determine that 3 is the most often used number and am required to return the position in the array it occurs. Any position is fine. For example, 0,2,4,6,7 are all valid solutions.开发者_如何学编程

Thoughts?

There are several ways to do this. One is to sort the array, so that you can count all similar values at once. Another is to use an associative array, a.k.a. a dictionary, where the values from A are keys and frequencies are the values associated with the keys.

I would create a map<int,int> to count the frequency of each element. Then use std::max_element with a custom function that compares the pair elements of the map by value. Then I would just use std::find on the array to find the first match.