added one pass solution and test case for 369 (#155)

Author: ashmichheda

src/main/java/com/fishercoder/solutions/_369.java

@@ -55,4 +55,33 @@ public ListNode plusOne(ListNode head) {
         }
     }
 
+    public static class Solution2 {
+
+        public ListNode plusOne(ListNode head) {
+            ListNode dummyNode = new ListNode(0);
+            dummyNode.next = head;
+
+            ListNode notNineNode = dummyNode;
+
+            // find the right most node value != 9
+            while (head != null) {
+                if (head.val != 9) {
+                    notNineNode = head;
+                }
+                head = head.next;
+            }
+
+            // increase the rightmost node value to 1
+            notNineNode.val ++;
+            notNineNode = notNineNode.next;
+
+            // set all the following node values with 9 to 0
+            while (notNineNode != null) {
+                notNineNode.val = 0;
+                notNineNode = notNineNode.next;
+            }
+            return dummyNode.val != 0 ? dummyNode : dummyNode.next;
+        }
+    }
+
 }

src/test/java/com/fishercoder/_369Test.java

@@ -0,0 +1,29 @@
+package com.fishercoder;
+
+import com.fishercoder.common.classes.ListNode;
+import com.fishercoder.common.utils.LinkedListUtils;
+import com.fishercoder.solutions._203;
+import com.fishercoder.solutions._369;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _369Test {
+
+    private static _369.Solution2 solution2;
+    private static ListNode head;
+    private static ListNode expected;
+
+    @BeforeClass
+    public static void setup() {
+        solution2 = new _369.Solution2();
+    }
+
+    @Test
+    public void test1() {
+        head = LinkedListUtils.contructLinkedList(new int[]{1, 2, 9});
+        expected = LinkedListUtils.contructLinkedList(new int[]{1, 3, 0});
+        assertEquals(expected, solution2.plusOne(head));
+    }
+}