This is a possible way to answer the methods for the Partial 1 in CS II class.

Partial1CSII.java

public class Partial1CSII {
	public static void main(String[] args) {

		// Calling exercise II
		System.out.println(lowest(4,3,-45));

		// Calling exercise III
		int[] numbers = new int[]{4, 20, 35, 4, 6};
		System.out.println(diff(numbers));

		// Calling exercise IV
		int[][] matrix = new int[][]{{1,2,3},{1,2,3},{1,2,3}};
		int[] sums = new int[matrix[0].length];
		sums = allColsSums(matrix);
		for (int i = 0; i < sums.length; i++) {
			System.out.println(sums[i]);
		}		

	}

	/*
	*	Exercise II, Partial 1 - CS II
	*	Method that receives 3 integers and returns the lowest among them.
	*
	*	This method considers if numbers are the same, controlled in the conditionals
	*	with the '<='  statement.
	*/
	public static int lowest(int a, int b, int c) {
		int lowest = a;
		if (a <= b && a <= c) 
			lowest = a;
		else if (b <= a && b <= c)
			lowest = b;
		else if (c <= a && c <= b)
			lowest = c;

		return lowest;
	}

	/*
	*	Exercise III, Partial 1 - CS II
	*	Method that receives an int array and returns the difference between the largest and
	*	the smallest number within the array.
	*
	*	This method has been simplified in only 1 loop to inspect only one time for
	*	the largest and the smallest. 
	*/
	public static int diff(int[] array) {
		int largest = array[0], smallest = array[0];

		for (int i = 0; i < array.length; i++) {
			if (smallest > array[i])
				smallest = array[i];
			if (largest < array[i])
				largest = array[i];
		}

		return largest - smallest;
	}


	/*
	*	Exercise IV, Partial 1 - CS II
	*	Method that receives an int 2D array and returns the sum of every column
	*	in an array format. 
	*
	*	The sum of column 0, will be stored in index 0 on the returned array and so forth for
	*	the other sums. 
	*/
	public static int[] allColsSums(int[][] a) {
		int[] array = new int[a[0].length];
		int sum = 0;

		for (int col = 0; col < a[0].length; col++) {
			for (int row = 0; row < a.length; row++) {
				sum += a[row][col];
			}
			array[col] = sum;
			sum = 0;
		}

		return array;

	}
}