Added _974.java (fishercoder1534#34)

varunu28 · fishercoder1534 · commit 86f932609f0b · 2019-01-13T20:59:47.000-08:00
diff --git a/README.md b/README.md
@@ -29,8 +29,9 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
-|976|[Largest Perimeter Triangle](https://leetcode.com/problems/largest-perimeter-triangle/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_976.java) | O(nlogn) | O(1) | |Easy| Math Array
-|973|[K Closest Points to Origin](https://leetcode.com/problems/k-closest-points-to-origin/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_973.java) | O(nlogn) | O(K) | |Easy| Math Sort
+|976|[Largest Perimeter Triangle](https://leetcode.com/problems/largest-perimeter-triangle/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_976.java) | O(nlogn) | O(1) | |Easy| Math Array 
+|974|[Subarray Sums Divisible by K](https://leetcode.com/problems/subarray-sums-divisible-by-k/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_974.java) | O(n) | O(n) | |Medium| Array|
+|973|[K Closest Points to Origin](https://leetcode.com/problems/k-closest-points-to-origin/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_973.java) | O(nlogn) | O(K) | |Easy| Math Sort|
 |970|[Powerful Integers](https://leetcode.com/problems/powerful-integers/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_970.java) | O(?) | O(1) | |Easy| Math
 |966|[Vowel Spellchecker](https://leetcode.com/problems/vowel-spellchecker/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_966.java) | O(hlogn) | O(n) | |Medium| Hash Table, String
 |965|[Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_965.java) | O(n) | O(h) | |Easy| DFS, recursion|
diff --git a/src/main/java/com/fishercoder/solutions/_974.java b/src/main/java/com/fishercoder/solutions/_974.java
@@ -0,0 +1,34 @@
+package com.fishercoder.solutions;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * 974. Subarray Sums Divisible by K
+ *
+ * Given an array A of integers, return the number of (contiguous, non-empty) subarrays that have a sum
+ * divisible by K.
+ * */
+
+public class _974 {
+    public static class Solution1 {
+        public int subarraysDivByK(int[] A, int K) {
+            int count = 0;
+            int sum = 0;
+            Map<Integer, Integer> map = new HashMap<>();
+            map.put(0, 1);
+
+            for (int i = 0; i < A.length; i++) {
+                sum = (sum + A[i]) % K;
+                if (sum < 0) {
+                    sum += K;
+                }
+
+                count += map.getOrDefault(sum, 0);
+                map.put(sum, map.getOrDefault(sum, 0) + 1);
+            }
+
+            return count;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_974Test.java b/src/test/java/com/fishercoder/_974Test.java
@@ -0,0 +1,22 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._974;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _974Test {
+
+    private static _974.Solution1 test;
+
+    @BeforeClass
+    public static void setUp() {
+        test = new _974.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(7, test.subarraysDivByK(new int[]{4, 5, 0, -2, -3, 1}, 5));
+    }
+}
