Created
January 31, 2022 10:57
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Insert value into LinkedList before other value. And set iterator to point on iserted value
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import org.junit.jupiter.api.Assertions; | |
import org.junit.jupiter.api.Test; | |
import java.util.LinkedList; | |
import java.util.List; | |
import java.util.ListIterator; | |
public class InsertBeforeTest { | |
private void insertBefore(int before, int val, ListIterator<Integer> iter) { | |
while(iter.hasNext()) { | |
Integer cur = iter.next(); | |
if (cur >= before) { | |
iter.previous(); | |
iter.add(val); | |
iter.previous(); | |
return; | |
} | |
} | |
iter.add(val); | |
iter.previous(); | |
} | |
@Test | |
public void testInsertAtStart() { | |
LinkedList<Integer> xs = new LinkedList<>(List.of(1, 2, 3)); | |
ListIterator<Integer> iter = xs.listIterator(); | |
insertBefore(1, 4, iter); | |
Assertions.assertFalse(iter.hasPrevious()); | |
Assertions.assertTrue(iter.hasNext()); | |
Assertions.assertEquals(4, iter.next()); | |
Assertions.assertEquals(List.of(4, 1, 2, 3), xs); | |
} | |
@Test | |
public void testInsertAtMiddle() { | |
LinkedList<Integer> xs = new LinkedList<>(List.of(1, 2, 3)); | |
ListIterator<Integer> iter = xs.listIterator(); | |
insertBefore(2, 4, iter); | |
Assertions.assertEquals(4, iter.next()); | |
Assertions.assertEquals(List.of(1, 4, 2, 3), xs); | |
} | |
@Test | |
public void testInsertAtEnd() { | |
LinkedList<Integer> xs = new LinkedList<>(List.of(1, 2, 3)); | |
ListIterator<Integer> iter = xs.listIterator(); | |
insertBefore(5, 4, iter); | |
Assertions.assertEquals(4, iter.next()); | |
Assertions.assertEquals(List.of(1, 2, 3, 4), xs); | |
} | |
} |
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