refactor 646

Author: fishercoder1534

README.md

@@ -40,7 +40,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |649|[Dota2 Senate](https://leetcode.com/problems/dota2-senate/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_649.java) | O(n) |O(n) | Medium | Greedy
 |648|[Replace Words](https://leetcode.com/problems/replace-words/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_648.java) | O(n) |O(n) | Medium | Trie
 |647|[Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_647.java) | O(n^2) |O(1) | Medium | DP
-|646|[Maximum Length of Pair Chain](https://leetcode.com/problems/maximum-length-of-pair-chain/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_646.java) | O(nlogn) |O(1) | Medium | DP
+|646|[Maximum Length of Pair Chain](https://leetcode.com/problems/maximum-length-of-pair-chain/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_646.java) | O(nlogn) |O(1) | Medium | DP, Greedy
 |645|[Set Mismatch](https://leetcode.com/problems/set-mismatch/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_645.java) | O(nlogn) |O(1) | Easy | 
 |644|[Maximum Average Subarray II](https://leetcode.com/problems/maximum-average-subarray-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_644.java) | |O(1) | Hard | Binary Search
 |643|[Maximum Average Subarray I](https://leetcode.com/problems/maximum-average-subarray-i/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_643.java) | O(n) |O(1) | Easy |

src/main/java/com/fishercoder/solutions/_646.java

@@ -21,7 +21,9 @@ Now, we define a pair (c, d) can follow another pair (a, b) if and only if b < c
  */
 public class _646 {
 
-    /**credit: https://discuss.leetcode.com/topic/96804/java-o-nlog-n-time-o-1-space*/
+    /**
+     * credit: https://discuss.leetcode.com/topic/96804/java-o-nlog-n-time-o-1-space
+     */
     public int findLongestChain(int[][] pairs) {
         Arrays.sort(pairs, (o1, o2) -> o1[1] - o2[1]);
         int result = 0;
@@ -30,7 +32,7 @@ public int findLongestChain(int[][] pairs) {
         while (++i < n) {
             result++;
             int curEnd = pairs[i][1];
-            while (i+1 < n && pairs[i+1][0] <= curEnd) {
+            while (i + 1 < n && pairs[i + 1][0] <= curEnd) {
                 /**This means, we'll keep incrementing i until pairs[i+1][0] is
                  * exactly greater than curEnd.*/
                 i++;
@@ -39,29 +41,4 @@ public int findLongestChain(int[][] pairs) {
         return result;
     }
 
-    public static void main(String... args) {
-        _646 test = new _646();
-
-//        int[][] pairs = new int[][]{
-//                {1,2},
-//                {2,3},
-//                {5,6},
-//                {3,4}
-//        };
-
-        int[][] pairs = new int[][]{
-                {9,10},
-                {-9,9},
-                {-6,1},
-                {-4,1},
-                {8,10},
-                {7,10},
-                {9,10},
-                {2,10}
-        };
-
-        int i = test.findLongestChain(pairs);
-        System.out.println(i);
-        System.out.println("Hello World!");
-    }
-}
+}

src/test/java/com/fishercoder/_646Test.java

@@ -0,0 +1,45 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._646;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _646Test {
+
+    private static _646 test;
+    private static int[][] pairs;
+
+    @BeforeClass
+    public static void setup() {
+        test = new _646();
+    }
+
+    @Test
+    public void test1() {
+        pairs = new int[][]{
+                {1,2},
+                {2,3},
+                {5,6},
+                {3,4}
+        };
+        assertEquals(3, test.findLongestChain(pairs));
+    }
+
+    @Test
+    public void test2() {
+        pairs = new int[][]{
+                {9,10},
+                {-9,9},
+                {-6,1},
+                {-4,1},
+                {8,10},
+                {7,10},
+                {9,10},
+                {2,10}
+        };
+        assertEquals(2, test.findLongestChain(pairs));
+    }
+
+}