refactor 14

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_14.java

@@ -4,42 +4,25 @@
  * 14. Longest Common Prefix
  *
  * Write a function to find the longest common prefix string amongst an array of strings.
+ *
+ * If there is no common prefix, return an empty string "".
+ *
+ * Example 1:
+ * Input: ["flower","flow","flight"]
+ * Output: "fl"
+ *
+ * Example 2:
+ * Input: ["dog","racecar","car"]
+ * Output: ""
+ * Explanation: There is no common prefix among the input strings.
+ *
+ * Note:
+ * All given inputs are in lowercase letters a-z.
  */
 
 public class _14 {
 
     public static class Solution1 {
-        public String longestCommonPrefix(String[] strs) {
-            if (strs.length == 0) {
-                return "";
-            }
-
-            int i = 0;
-            String prefix = "";
-            String result;
-            boolean broken = false;
-            while (true) {
-                i++;
-                result = prefix;
-                if (i > strs[0].length()) {
-                    break;//this will break out the while loop
-                }
-                prefix = strs[0].substring(0, i);
-                for (String word : strs) {
-                    if (i > word.length() || !word.startsWith(prefix)) {
-                        broken = true;
-                        break;//this will only break out of the for loop
-                    }
-                }
-                if (broken) {
-                    break;//this will break out the while loop
-                }
-            }
-            return result;
-        }
-    }
-
-    public static class Solution2 {
         //horizontal scan
         public String longestCommonPrefix(String[] strs) {
             if (strs.length == 0) {
@@ -58,7 +41,7 @@ public String longestCommonPrefix(String[] strs) {
         }
     }
 
-    public static class Solution3 {
+    public static class Solution2 {
         //vertical scan
         public String longestCommonPrefix(String[] strs) {
             if (strs.length == 0) {

src/test/java/com/fishercoder/_14Test.java

@@ -9,38 +9,61 @@
 public class _14Test {
     private static _14.Solution1 solution1;
     private static _14.Solution2 solution2;
-    private static _14.Solution3 solution3;
     private static String[] strs;
 
     @BeforeClass
     public static void setup() {
         solution1 = new _14.Solution1();
         solution2 = new _14.Solution2();
-        solution3 = new _14.Solution3();
     }
 
     @Test
     public void test1() {
         strs = new String[]{"a", "b"};
         assertEquals("", solution1.longestCommonPrefix(strs));
         assertEquals("", solution2.longestCommonPrefix(strs));
-        assertEquals("", solution3.longestCommonPrefix(strs));
     }
 
     @Test
     public void test2() {
         strs = new String[]{"leetcode", "lead"};
         assertEquals("le", solution1.longestCommonPrefix(strs));
         assertEquals("le", solution2.longestCommonPrefix(strs));
-        assertEquals("le", solution3.longestCommonPrefix(strs));
     }
 
     @Test
     public void test3() {
         strs = new String[]{"leetcode", "code"};
         assertEquals("", solution1.longestCommonPrefix(strs));
         assertEquals("", solution2.longestCommonPrefix(strs));
-        assertEquals("", solution3.longestCommonPrefix(strs));
+    }
+
+    @Test
+    public void test4() {
+        strs = new String[]{"flower", "flow", "flight"};
+        assertEquals("fl", solution1.longestCommonPrefix(strs));
+        assertEquals("fl", solution2.longestCommonPrefix(strs));
+    }
+
+    @Test
+    public void test5() {
+        strs = new String[]{};
+        assertEquals("", solution1.longestCommonPrefix(strs));
+        assertEquals("", solution2.longestCommonPrefix(strs));
+    }
+
+    @Test
+    public void test6() {
+        strs = new String[]{"a"};
+        assertEquals("a", solution1.longestCommonPrefix(strs));
+        assertEquals("a", solution2.longestCommonPrefix(strs));
+    }
+
+    @Test
+    public void test7() {
+        strs = new String[]{"c", "c"};
+        assertEquals("c", solution1.longestCommonPrefix(strs));
+        assertEquals("c", solution2.longestCommonPrefix(strs));
     }
 
 }