Return kth element

premaseem · premaseem · commit b359683f4563 · 2019-09-02T15:33:56.000-05:00
diff --git a/src/crackingTheCodingInterview/chap2/ReturnKToLast.java b/src/crackingTheCodingInterview/chap2/ReturnKToLast.java
@@ -0,0 +1,56 @@
+package crackingTheCodingInterview.chap2;
+
+import me.premaseem.myLib.MyDLLNode;
+import org.junit.Test;
+
+public class ReturnKToLast {
+
+    // Test Driven Development by Aseem Jain
+    @Test
+    public void test() {
+
+        int[] in = {2, 4, 4, 5, 9, 6, 8, 2};
+        MyDLLNode head = new MyDLLNode(in);
+
+        // get 3rd from last
+        assert solution1(head,2).data == 8;
+        assert solution2(head,2).data == 8;
+
+    }
+
+    // Basic solution
+    private MyDLLNode solution1(MyDLLNode head, int k) {
+
+        // count total number in one loop.
+        // iterate for last - k to return element
+        MyDLLNode c = head;
+        int len =0;
+        while(c != null){
+            len++;
+            c = c.next;
+        }
+
+        c = head;
+        for (int i = 1; i <= len-k ; i++, c = c.next) {
+
+        }
+            return c;
+    }
+
+    private MyDLLNode solution2(MyDLLNode head, int k) {
+
+        // count total number in one loop.
+        // iterate for last - k to return element
+        MyDLLNode c = head;
+        while(c.next != null){
+            c = c.next;
+        }
+
+        MyDLLNode last = c;
+
+        for (int i = 1; i < k ; i++, last = last.prev) {
+
+        }
+        return last;
+    }
+}
