Add singleLinkedList code

Author: jbee37142

src/test/java/algorithm/linkedlist/SingleLinkedListTest.java

@@ -0,0 +1,138 @@
+package algorithm.linkedlist;
+
+import org.junit.Test;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.Stack;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class SingleLinkedListTest {
+
+    @Test
+    public void test() {
+        assertThat("", is(testFunction()));
+    }
+
+    public String testFunction() {
+        return "";
+    }
+
+    public class Node {
+        int data;
+        Node next;
+    }
+
+    private class SingleLinkedList {
+        private Node head;
+
+        public void addToHead(int n) {
+            Node newNode = new Node();
+            newNode.data = n;
+            head.next = newNode;
+            head = newNode;
+        }
+
+        /*
+            TASK
+            첫번째 원소를 제거하라.
+        */
+
+        public void removeFirst() {
+            if (head == null) {
+                throw new RuntimeException("Not found");
+            }
+//            head = head.next;
+            Node temp = head;
+            head = null;
+            head = temp.next;
+        }
+
+        /*
+            TASK
+            중복된 원소를 제거하라.
+        */
+
+        public void removeDuplicateElm() {
+            Set<Integer> set = new HashSet<>();
+            Node prev = null;
+            Node start = head;
+            while (start != null) {
+                if (set.contains(start.data)) {
+                    if (prev == null) {
+                        break ;
+                    }
+                    prev.next = start.next;
+                } else {
+                    set.add(start.data);
+                    prev = start;
+                }
+                start = start.next;
+            }
+        }
+
+        /*
+            TASK
+            역순으로 출력하라.
+         */
+
+        public void reverse() {
+            Node prev = null;
+            Node start = head;
+            Node next = null;
+            while (start != null) {
+                next = start.next;
+                start.next = prev;
+                prev = next;
+            }
+        }
+
+        /*
+            TASK
+            k번째 원소를 찾아라.
+         */
+
+        public Node kthToLast(int k) {
+            Node result = head;
+            if (k < 0) {
+                return null;
+            }
+            int count = 0;
+            while(count < k) {
+                result = head.next;
+                head = head.next;
+                count++;
+            }
+            return result;
+        }
+
+        /*
+            TASK
+            회문인지 판단하라.
+         */
+
+        public boolean isPlaindrome() {
+            Stack<Node> stack = new Stack<>();
+            Node node1 = head;
+            Node node2 = head;
+            while (node1 != null && node2 != null) {
+                stack.push(node1);
+                node1 = head.next;
+                node2 = head.next.next;
+            }
+            if (node2 != null) { //홀수인 경우
+                node1 = node1.next;
+            }
+
+            while (node1 != null) {
+                if (stack.pop().data != node1.data) {
+                    return false;
+                }
+                node1 = node1.next;
+            }
+            return true;
+        }
+    }
+}