From d5dc5788bb85e59be150cd25ecaf26c1b190fb9f Mon Sep 17 00:00:00 2001
From: ankit351104 <91881708+ankit351104@users.noreply.github.com>
Date: Thu, 27 Oct 2022 16:59:05 +0530
Subject: [PATCH] Subarray Sum Divisible by K (Leetcode 974)

A classic sliding window approach in Java
---
 Medium/Subarray Sum Divisible by K.java | 27 +++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 Medium/Subarray Sum Divisible by K.java

diff --git a/Medium/Subarray Sum Divisible by K.java b/Medium/Subarray Sum Divisible by K.java
new file mode 100644
index 0000000..c1c9d24
--- /dev/null
+++ b/Medium/Subarray Sum Divisible by K.java	
@@ -0,0 +1,27 @@
+class Solution {
+    public int subarraysDivByK(int[] nums, int k) {
+        int count =0;
+        int sum =0;
+        int rem =0;
+        HashMap<Integer,Integer> map = new HashMap<>();
+        map.put(0,1); //initially sum is 0 and it appeared once already
+        
+        for(int num:nums){
+            sum+=num;
+            rem=sum%k;
+            
+            if(rem<0){
+                rem+=k; // if k=7 and rem = -2 then rem+k =2 and the gap betwen 2 and -5 is 7 which is divisible by 7
+            }
+            if(map.containsKey(rem)){
+                count+=map.get(rem);
+                map.put(rem, map.get(rem)+1);
+            }
+            else{
+                map.put(rem,1);
+            }
+        }
+        System.out.println(map.entrySet());
+        return count;
+    }
+}
\ No newline at end of file