add 1524

fishercoder1534 · fishercoder1534 · commit 66beb602bc62 · 2020-07-25T10:11:20.000-07:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ &#9733;
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1524|[Number of Sub-arrays With Odd Sum](https://leetcode.com/problems/number-of-sub-arrays-with-odd-sum/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1524.java) | |Medium|Array, Math|
 |1523|[Count Odd Numbers in an Interval Range](https://leetcode.com/problems/count-odd-numbers-in-an-interval-range/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1523.java) | |Easy|Math|
 |1518|[Water Bottles](https://leetcode.com/problems/water-bottles/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1518.java) | |Easy|Greedy|
 |1514|[Path with Maximum Probability](https://leetcode.com/problems/path-with-maximum-probability/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1514.java) | |Medium|Graph|
diff --git a/src/main/java/com/fishercoder/solutions/_1524.java b/src/main/java/com/fishercoder/solutions/_1524.java
@@ -0,0 +1,46 @@
+package com.fishercoder.solutions;
+
+public class _1524 {
+    public static class Solution1 {
+        /**
+         * This brute force solution will throw exceed time limit exceeded exception on LeetCode.
+         */
+        public int numOfSubarrays(int[] arr) {
+            long oddCount = 0;
+            for (int i = 0; i < arr.length; i++) {
+                long subTotal = 0;
+                for (int j = i; j < arr.length; j++) {
+                    subTotal += arr[j];
+                    if (subTotal % 2 != 0) {
+                        oddCount++;
+                    }
+                }
+            }
+            return (int) oddCount % 1000000007;
+        }
+    }
+
+    public static class Solution2 {
+        public int numOfSubarrays(int[] arr) {
+            int odd = 0;
+            int even = 1;
+            long count = 0;
+            int sum = 0;
+            for (int num : arr) {
+                sum += num;
+                if (sum % 2 == 0) {
+                    count += odd;
+                } else {
+                    count += even;
+                }
+                if (sum % 2 == 0) {
+                    even++;
+                } else {
+                    odd++;
+                }
+                count %= 1000000007;
+            }
+            return (int) count % 1000000007;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1524Test.java b/src/test/java/com/fishercoder/_1524Test.java
@@ -0,0 +1,44 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1524;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class _1524Test {
+    private static _1524.Solution1 solution1;
+    private static _1524.Solution2 solution2;
+    private static int[] arr;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1524.Solution1();
+        solution2 = new _1524.Solution2();
+    }
+
+    @Test
+    public void test1() {
+        arr = new int[]{1, 3, 5};
+        assertEquals(4, solution1.numOfSubarrays(arr));
+    }
+
+    @Test
+    public void test2() {
+        arr = new int[]{2, 4, 6};
+        assertEquals(0, solution1.numOfSubarrays(arr));
+    }
+
+    @Test
+    public void test4() {
+        arr = new int[]{1, 3, 5};
+        assertEquals(4, solution2.numOfSubarrays(arr));
+    }
+
+    @Test
+    public void test5() {
+        arr = new int[]{2, 4, 6};
+        assertEquals(0, solution2.numOfSubarrays(arr));
+    }
+
+}
