Various Methods for the CAB201 (Sem 2 16) Practice exam

201 Practice Exam.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

// Q1 A
public static bool IsLeapYear(int year) {
    return year % 4 == 0 && (!(year % 100 == 0) || (year % 400 == 0));
}

// Q1 B
public static bool IsArraySorted(int[] numbers) {
    int[] sortedArray = numbers.ToArray();
    Array.Sort(sortedArray);
    return Enumerable.SequenceEqual(numbers, sortedArray) || Enumerable.SequenceEqual(numbers.Reverse(), sortedArray);
}

// Q2 A
public void Reverse(double[] values, int start, int finish) {
    for (int i = 0; i <= (finish - (start * 2));i++) {
        Swap(values, start + i, finish - i);
    }
}

// Q2 B
public static int LastPairOfDuplicates(int[] anArray) {
    int lastItem = anArray[anArray.Length-1];
    for (int i = anArray.Length - 2; i >= 0; i--) {
        if (anArray[i] == lastItem) {
            return i;
        }
        lastItem = anArray[i];
    }
    return -1;
}

// Q3 A
public static bool NumberValid(int number) {
    string numberString = number.ToString();
    int sum = 0;
    if (numberString.Length == 9) {
        for (int i = 0; i < 9; i++) {
            sum += Convert.ToInt32(char.GetNumericValue(numberString[i])) * (9 - i);
        }
        if (sum % 11 == 0) {
            return true;
        }
    }
    return false;
}

// Q3 B
static int CalculateAge(Date birthday, Date today) {
    int yearDifference = today.GetYear() - birthday.GetYear();
    if (today.GetMonth() >= birthday.GetMonth()){
        if (today.GetDay() >= birthday.GetDay()) {
            return yearDifference;
        }
    }
    return yearDifference - 1;
}