Skip to content

Exercise 7_31 is not solved correctly #40

@jdeisenberg

Description

@jdeisenberg

The instructions say: “Implement the method in a way that takes at most list1.length + list2.length comparisons”, but your sort takes many more than that.

Count the number of comparisons in the sort

public static void sort(int[] list) {
    int nCompare = 0;
		for (int i = 0; i < list.length - 1; i++) {
			int min = list[i];
			int minIndex = i;

			for (int j = i + 1; j < list.length; j++) {
				nCompare++;
				if (list[j] < min) {
					min = list[j];
					minIndex = j; 
				}					
			}

			if (minIndex != i) {
				list[minIndex] = list[i];
				list[i] = min;
			}
		}
		System.out.println("Total compares: " + nCompare);
	}
}

For arrays [10, 20, 30, 40, 50] and [1, 2, 3, 4, 5] in that order, it takes 45 comparisons, which is far more than the 10 that the exercise allows.

(By the way, several students in my class copied this wrong solution and lost a large number of points for doing it incorrectly -- and for plagiarism.)

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions