max.hid

// Compare these two inputs.  This algorithm returns early as soon as it
// finds the max value, so it is much faster if the max value is at the
// beginning of the array.

// const int[] default = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
const int[] default = [9, 8, 7, 6, 5, 4, 3, 2, 1, 0];

int @max(const int[] arr) {
    try {
        int max_val = arr[0];
        for (int i = 1; i < arr.length; i += 1) {
            if (arr[i] > max_val) {
                max_val = arr[i];
                preempt {
                    // There are no larger values, so return early.
                    return max_val;
                }
            }
        }

        // Reaching the end of the array without returning is defeat
        !is_defeat();
    } undo {
        // First item was the max, return it
        // The typechecker knows !is_defeat() is guaranteed defeat, so
        // we can put the return here without it complaining.
        return arr[0];
    }
}

empty write_array(const int[] arr) {
    write('[');
    for (int i = 0; i < arr.length; i += 1) {
        if (i != 0) {
            write(", ");
        }
        write(arr[i]);
    }
    write(']');
}

empty @is_you(int[] nums) {
    if (nums) {
        write("Max value: ");
        writeln(@max(nums));
    } else {
        write("Array: ");
        write_array(default);
        writeln();
        write("Max value: ");
        writeln(@max(default));
    }
}