Canonical Solutions - Arrays

Traverse Array

// diplay all the values in an array in order
public static void displayForward( int[] a )
{
	for ( int n : a )
		out.println(n);
}

Traverse backwards

// diplay all the values in an array in *reverse* order
public static void displayBackward( int[] a )
{
	for ( int i=a.length-1 ; i>=0; i-- )
		out.println( a[i] );
}

Find smallest

// find the smallest value in an array (return smallest)
public static int findSmallest( int[] arr )
{
	int min = Integer.MAX_VALUE;
	for ( int v : arr )
		if ( v < min )
			min = v;
	return min;
}

Find largest

// find the largest value in an array (return largest)
public static int findLargest( int[] a )
{
	int max = Integer.MIN_VALUE;
	for ( int q : a )
		if ( q > max )
			max = q;
	return max;
}

Sum Values

// get the sum of all the values in an array (return sum)
public static int getSum( int[] values ) // we're up all night to...
{
	int totes = 0;
	for ( int n : values )
		totes += n;
	return totes;
}

Filter Values

// display all values greater than some threshold (filter) in an array
public static void displaySome( int[] thingys, int limit )
{
	for ( int t : thingys )
		if ( t > limit )
			out.println(t);
}

Locate value

// find the location (index) for a value in an array (return slot)
public static int locate( int[] arr, int toFind )
{
	for ( int i=0 ; i<arr.length; i++ )
		if ( arr[i] == toFind )
			return i;
	return -1;
}

Is value present?

// determine if a value is present in an array (return true/false)
public static boolean contains( int[] arr, int toFind )
{
	for ( int k : arr )
		if ( k == toFind )
			return true;
	return false;
}

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Canonical Solutions - ArrayLists

Traverse ArrayList

// diplay all the values in an ArrayList in order
public static void displayForward( ArrayList<String> names )
{
	for ( String s : names )
		out.println(s);
}

Reverse Traversal

// diplay all the values in an ArrayList in *reverse* order
public static void displayBackward( ArrayList<String> winners )
{
	for ( int i=winners.size()-1 ; i>=0; i-- )
		out.println( winners.get(i) );
}

Find smallest or largest

// find the smallest value in an ArrayList (return smallest)
public static String findSmallest( List<String> list )
{
	String min = "";
	for ( String v : list )
		if ( v.compareTo(min) < 0 )
			min = v;
	return min;
}

Sum Values

// get the sum of all the values in an ArrayList (return sum)
public static int getTotal( ArrayList<Double> sales )
{
	int sum = 0;
	for ( double s : sales )
		sum += s;
	return sum;
}

Filter Values

// display all values greater than some threshold (filter) in an ArrayList
public static void displaySome( ArrayList<Integer> stuff, int limit )
{
	for ( int t : stuff )
		if ( t > limit )
			out.println(t);
}

Locate value

// find the location (index) for a value in an ArrayList (return slot)
public static int locate( ArrayList<String> nicks, String wanted )
{
	for ( int i=0 ; i<nicks.size(); i++ )
		if ( nick.get(i).equals(wanted) )
			return i;
	return -1;
}

Is value present?

// determine if a value is present in an ArrayList (return true/false)
public static boolean contains( ArrayList<Integer> arr, int toFind )
{
	for ( int k : arr )
		if ( k == toFind )
			return true;
	return false;
}