ArrayExamples.java

public class ArrayExamples {

  // Changes the input array to be in reversed order
  static void reverseInPlace(int[] arr) {
    for(int i = 0; i < arr.length / 2; i += 1) {
      int tmp = arr[i];
      arr[i] = arr[arr.length - i - 1];
      arr[arr.length - i - 1] = tmp;
    } 

    /*
     * error: overwrites arr[i] on first half without saving it for assignment later
     * original:
      for(int i = 0; i < arr.length; i += 1) {
        arr[i] = arr[arr.length - i - 1];
      }
    */
  }

  // Returns a *new* array with all the elements of the input array in reversed
  // order
  static int[] reversed(int[] arr) {
    int[] newArray = new int[arr.length];
    for(int i = 0; i < arr.length; i += 1) {
      newArray[i] = arr[arr.length - i - 1];
    }
    return newArray;

    /*
     * error: Values from the empty new array are being assigned to the old array, 
              and it should be the other way around.
     * original:
        int[] newArray = new int[arr.length];
        for(int i = 0; i < arr.length; i += 1) {
          arr[i] = newArray[arr.length - i - 1];
        }
        return arr;
    */
  }

  // Averages the numbers in the array (takes the mean), but leaves out the
  // lowest number when calculating. Returns 0 if there are no elements or just
  // 1 element in the array
  static double averageWithoutLowest(double[] arr) {
    if(arr.length < 2) { return 0.0; }
    double lowest = arr[0];
    for(double num: arr) {
      if(num < lowest) { lowest = num; }
    }
    double sum = 0;
    for(double num: arr) {
      sum += num;
    }
    sum -= lowest;
    return sum / (arr.length - 1);

    /*
     * error: Same number might get skipped if equal to the lowest 
              (only one of the lowest number should be dropped, 
              but function will drop duplicates too)
     * original:
      if(arr.length < 2) { return 0.0; }
        double lowest = arr[0];
      for(double num: arr) {
        if(num < lowest) { lowest = num; }
      }
      double sum = 0;
      for(double num: arr) {
        if(num != lowest) { sum += num; }
      }
      return sum / (arr.length - 1);
    */
  }


}