[Codility] Lesson 6 - Distinct

Task discription

Write a function

int solution(vector<int> &A);

that, given an array A consisting of N integers, returns the number of distinct values in array A.

For example, given array A consisting of six elements such that:

A[0] = 2    A[1] = 1    A[2] = 1
A[3] = 2    A[4] = 3    A[5] = 1

the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.

Write an efficient algorithm for the following assumptions:

• N is an integer within the range [0..100,000];
• each element of array A is an integer within the range [−1,000,000..1,000,000].

Source code

#include <algorithm>

int solution(vector<int> &A) {
    sort(A.begin(), A.end());
    A.erase(unique(A.begin(), A.end()), A.end());

    return A.size();
}