1524_Number_of_SubArrays_with_Odd_Sum.java

Author: vishwajeetmishra4

JAVA/1524_Number_of_SubArrays_with_Odd_Sum.java

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+// Problem Number: 1524
+
+// Problem Number of Sub-Array with Odd Sum.
+
+class Solution {
+    public int numOfSubarrays(int[] arr) {
+        int MOD = 1000000007; // since answer can be very long thus moduls 10^9+7 (as directed)
+        int odd_count = 0; 
+        int even_count = 1;
+        int prefix_sum = 0;
+        int result = 0;
+
+        for (int i=0; i<arr.length; i++) {
+            prefix_sum += arr[i];
+            
+            if (prefix_sum % 2 == 0) {
+                result = (result + odd_count) % MOD;
+                even_count++;
+            } else {
+                result = (result + even_count) % MOD;
+                odd_count++;
+            }
+        }
+        
+        return result;
+        
+        
+    }
+}