mardi 24 mai 2016

Implementing the Fisher-Yates shuffling algorithm for a 2-D array (C++)

I have a 2-D array (10 x 10) which has been populated with the numbers 1-100. I am trying to use a Fisher-Yates shuffle to randomly redistribute the values in the array without repetition.

I am able to repopulate the array with random numbers 1-100, however I still get repeating values, and even get 0s (which should not happen).

void shuffleArray(int array[][10], int count) {
    srand(time(NULL));
    for (int i = 10, k = 0; i > 0; i--) {
        for (int j = 10; j > 0; j--, k++) { 
            int newValue = rand() % (count - k);
            array[i][j] = newValue;
        }
    }
}

int main(){
//Create and populate the array with the numbers 1-100
    int array[10][10]{ { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 },
                       { 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 },
                       { 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 },
                       { 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 },
                       { 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 },
                       { 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 },
                       { 61, 62, 63, 64, 65, 66, 67, 68, 69, 70 },
                       { 71, 72, 73, 74, 75, 76, 77, 78, 79, 80 },
                       { 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 },
                       { 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 } };

//Call the array shuffling function
shuffleArray(array, 100);


//Display the array to the screen for debug purposes
for (int i = 0; i < 10; i++) {
    for (int j = 0; j < 10; j++) {
        if (array[i][j] < 10) {
            cout << "   " << array[i][j] << "  ";
        }
        else if (array[i][j] == 100) {
            cout << " " << array[i][j] << "  ";
        }
        else {
            cout << "  " << array[i][j] << "  ";
        }
    }
    cout << "\n\n\n";

    return 0;
}




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