LoopDetectionSolutionOneTest.java

import static org.junit.Assert.*;

import org.junit.Test;

public class LoopDetectionSolutionOneTest {

    private LNode createLinkedList(int numOfNode, int headNodePos) {

        LNode head = new LNode(0, null);

        LNode current = new LNode(1, null);

        

        LNode loopHead = null;

        if(headNodePos == 1) loopHead = current;

        head.next = current;

        for(int i = 2; i <= numOfNode; i++) {

            current.next = new LNode(i, null);

            current = current.next;

            if(i == headNodePos) {

                loopHead = current;

            }

        }

        current.next = loopHead;

        return head;

    }

    

    private LNode getHeadNode(LNode head, int headNodePos) {

        LNode current = head.next;

        for(int i = 1; i < headNodePos; i++) {

            current = current.next;

        }

        return current;

    }

    

    @Test

    public void testLoop() {

        

        int numOfNode = 5;

        int headNodePos = 2;

        LNode head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertTrue(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertTrue(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 5;

        headNodePos = 5;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertTrue(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertTrue(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 5;

        headNodePos = 1;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertTrue(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertTrue(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 1;

        headNodePos = 1;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertTrue(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertTrue(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 7;

        headNodePos = 5;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertTrue(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertTrue(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 800;

        headNodePos = 3;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertTrue(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertTrue(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

    }

    

    @Test

    public void testNoLoop() {

        

        int numOfNode = 5;

        int headNodePos = 0;

        LNode head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertFalse(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertFalse(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 1;

        headNodePos = 0;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertFalse(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertFalse(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 7;

        headNodePos = 0;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertFalse(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertFalse(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        numOfNode = 800;

        headNodePos = 0;

        head = createLinkedList(numOfNode, headNodePos);

        LoopDetectionSolutionOne.printResult(head, getHeadNode(head, headNodePos));

        assertFalse(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertFalse(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

    }

    

    @Test

    public void testNull() {

        LNode head = null;

        LoopDetectionSolutionOne.printResult(head, null);

        assertFalse(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertFalse(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

        

        head = new LNode(0, new LNode(1, null));

        LoopDetectionSolutionOne.printResult(head, null);

        assertFalse(LoopDetectionSolutionOne.hasLoopBrutalForce(head));

        assertFalse(LoopDetectionSolutionOne.hasLoopSlowFastPointer(head));

    }

}