%% CS 310 Team Lab 7: Nesting and Debugging
% SOLUTION - Spring 2013

%% Problem 1: Create a multiplication table

clear
matrix = zeros(25, 25);
for row = 1 : 25
    for col = 1 : 25
        matrix(row, col) = row * col;
    end
end
matrix

%% Problem 2: Calculate bonuses for division 1 employees

clear
data = load('division1.txt');
[rows, cols] = size(data);  % find the number of rows and cols
bonus = 0;                  % initialize total bonus amount to 0
for r = 1 :  rows           % for each employee
    
    % if the employee gets a bonus, calculate it and it to the total
    if data(r, 3)  % or could do: if data(r, 3) == 1
        bonus = bonus + 0.05*data(r, 2);
    end
end

disp(['Total bonus for Division 1 = $', num2str(bonus)])
        
%% Problem 3: Calculate bonuses for all four divisions

clear
N = 4;
total_bonus = 0;          % initialize total bonus amount to 0
div_bonus = zeros(1, N);  % stores bonus amount for each division

for d = 1:N                                      % for each division
    filename = ['division' num2str(d) '.txt'];   % load division's info
    data = load(filename);
    
    div_bonus(d) = 0;             % initialize this division's bonus to 0
    [rows, cols] = size(data);
    for r = 1 :  rows             % for each employee
        
        % if the employee is getting a bonus
        if data(r, 3)  % or could do: if data(r, 3) == 1
            bonus = 0.05*data(r, 2);             % compute bonus
            div_bonus(d) = div_bonus(d) + bonus; % add to division total
            total_bonus = total_bonus + bonus;   % add to overall total
        end
    end 
end

% display the bonuses for each division as well as the total bonus amount
for d = 1:N
    disp(['Total bonus for division ', num2str(d), ' = $', ...
          num2str(div_bonus(d))]);
end
disp(['Total bonus for all divisions = $', num2str(total_bonus)]);

%% Problem 4: Find the prime factors of a positive integer

clear

% prompt the user for a value
value = input('Enter a positive integer or 0 to quit: ');

% NOTE: publishing does not work if there is user input, so when 
% publishing, we comment out the line above and replace it with
% value = 495;

while value ~= 0        % while the user has not chosen the "quit" option
    
    % if the value is a positive integer
    if value > 0 && floor(value) == value
        
        factors = [];             % initialize factors list to empty list
        V = value;                % copy value into V
        for p = 2 : V/2           % for each number p between 1 and V/2
           if isprime(p)          % if p is prime
               
               while mod(V, p) == 0    % while V is evenly divisible by p
                   factors = [factors p];   % add p as a factor
                   V = V/p;                 % divide V by p to "remove" p
               end
               
           end
        end
        
        % display all the factors
        disp(['The factors of ', num2str(value), ' are: '])
        disp(factors)
        
    else % display an error message indicating what are valid values
        disp('Invalid input - value must be 0 or a positive integer')
    end
    
    % get the next value from the user
    value = input('Enter a positive integer or 0 to quit: ');
    
    % NOTE: publishing does not work if there is user input, so when 
    % publishing, we comment out the line above and replace it with
    % value = 0;

end

%% Problem 5: Count the number of primes between 1 and 100

clear
count = 0;
for n = 1 : 100
    if isprime(n)
        count = count + 1;
    end
end
disp(['There are ', num2str(count), ' primes between 1 and 100'])

%% Problem 6: Find and display the 25th prime number

clear
count = 0;
n = 1;     % start checking numbers at 1
while count < 25
    if isprime(n)
        count = count + 1;
    end
    n = n + 1;
end

% At the end of this loop, n will be 1 more than the 25th prime, so we'll
% need to take this into account.

disp(['The 25th prime is ', num2str(n-1)])