function centroids = computeCentroids(X, idx, K)
    %% COMPUTECENTROIDS returs the new centroids by computing the means of the 
    %data points assigned to each centroid.
    %   centroids = COMPUTECENTROIDS(X, idx, K) returns the new centroids by 
    %   computing the means of the data points assigned to each centroid. It is
    %   given a dataset X where each row is a single data point, a vector
    %   idx of centroid assignments (i.e. each entry in range [1..K]) for each
    %   example, and K, the number of centroids. You should return a matrix
    %   centroids, where each row of centroids is the mean of the data points
    %   assigned to it.
    %

    % Useful variables
    [m, n] = size(X);

    % You need to return the following variables correctly.
    centroids = zeros(K, n);
    
    % ====================== YOUR CODE HERE ======================
    % Instructions: Go over every centroid and compute mean of all points that
    %               belong to it. Concretely, the row vector centroids(i, :)
    %               should contain the mean of the data points assigned to
    %               centroid i.
    %
    % Note: You can use a for-loop over the centroids to compute this.
    %
    for k = 1 : K
        centroids(k, :) = mean(X(idx == k, :));
    end
end

