Small Steps III — Thinking with Programs

Counting occurrences of the largest value

Count occurrences of the largest value.

What you will learn

Combining two procedures you already know can solve a new problem.

Try it

void small_main()
{
    Array<int> numbers = {4, 9, 2, 9, 7};

    int largest = numbers[0];
    int count_largest = 0;

    for (int i = 0; i < numbers.length(); i = i + 1)
        if (numbers[i] > largest)
            largest = numbers[i];

    for (int i = 0; i < numbers.length(); i = i + 1)
        if (numbers[i] == largest)
            count_largest = count_largest + 1;

    print("Largest: ", largest);
    print("How many: ", count_largest);
}

First find the maximum, then use a second loop to count elements equal to it. The output is Largest: 9 and How many: 2.

Make each step's responsibility clear before trying to combine the two loops. The array must contain at least one element.

Exercise

First find the Array's largest value, then count how often it occurs in a second loop.

void small_main()
{
    Array<int> numbers = {5, 9, 2, 9, 9, 4};

    // find largest, then count it.
}

Hint

The first loop finds largest; the second counts occurrences of numbers[i] == largest.

void small_main()
{
    Array<int> numbers = {5, 9, 2, 9, 9, 4};
    int largest = numbers[0];

    for (int i = 1; i < numbers.length(); i = i + 1)
        if (numbers[i] > largest)
            largest = numbers[i];

    int count = 0;

    for (int i = 0; i < numbers.length(); i = i + 1)
        if (numbers[i] == largest)
            count = count + 1;

    print("Largest: ", largest);
    print("Count: ", count);
}