refactor 560

fishercoder1534 · fishercoder1534 · commit ea31c7b10fff · 2019-07-02T09:05:22.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_560.java b/src/main/java/com/fishercoder/solutions/_560.java
@@ -17,27 +17,32 @@
  */
 public class _560 {
 
-    /**credit: https://discuss.leetcode.com/topic/87850/java-solution-presum-hashmap
-     * We know the key to solve this problem is SUM[i, j].
-     * So if we know SUM[0, i - 1] and SUM[0, j],
-     * then we can easily get SUM[i, j] via (SUM[0, j] - SUM[0, i-1]).
-     * To achieve this, we just need to go through the array,
-     * calculate the current sum and save number of all seen PreSum to a HashMap.
-     *
-     * Time complexity O(n), Space complexity O(n).*/
-    public int subarraySum(int[] nums, int k) {
-        Map<Integer, Integer> preSum = new HashMap();
-        int sum = 0;
-        int result = 0;
-        preSum.put(0, 1);
-        for (int i = 0; i < nums.length; i++) {
-            sum += nums[i];
-            if (preSum.containsKey(sum - k)) {
-                result += preSum.get(sum - k);
+    public static class Solution1 {
+
+        /**
+         * credit: https://discuss.leetcode.com/topic/87850/java-solution-presum-hashmap
+         * We know the key to solve this problem is SUM[i, j].
+         * So if we know SUM[0, i - 1] and SUM[0, j],
+         * then we can easily get SUM[i, j] via (SUM[0, j] - SUM[0, i-1]).
+         * To achieve this, we just need to go through the array,
+         * calculate the current sum and save number of all seen PreSum to a HashMap.
+         * <p>
+         * Time complexity O(n), Space complexity O(n).
+         */
+        public int subarraySum(int[] nums, int k) {
+            Map<Integer, Integer> preSum = new HashMap();
+            int sum = 0;
+            int result = 0;
+            preSum.put(0, 1);
+            for (int i = 0; i < nums.length; i++) {
+                sum += nums[i];
+                if (preSum.containsKey(sum - k)) {
+                    result += preSum.get(sum - k);
+                }
+                preSum.put(sum, preSum.getOrDefault(sum, 0) + 1);
             }
-            preSum.put(sum, preSum.getOrDefault(sum, 0) + 1);
+            return result;
         }
-        return result;
     }
 
 }
diff --git a/src/test/java/com/fishercoder/_560Test.java b/src/test/java/com/fishercoder/_560Test.java
@@ -10,23 +10,23 @@
  * Created by fishercoder on 4/29/17.
  */
 public class _560Test {
-    private static _560 test;
+    private static _560.Solution1 solution1;
     private static int expected;
     private static int actual;
     private static int[] nums;
     private static int k;
 
     @BeforeClass
     public static void setup() {
-        test = new _560();
+        solution1 = new _560.Solution1();
     }
 
     @Test
     public void test1() {
         nums = new int[]{1, 1, 1};
         k = 2;
         expected = 2;
-        actual = test.subarraySum(nums, k);
+        actual = solution1.subarraySum(nums, k);
         assertEquals(expected, actual);
     }
 }
