Create 523-Continuous-Subarray-Sum.java

Author: SharmaTushar1

Diff for: java/523-Continuous-Subarray-Sum.java

@@ -0,0 +1,20 @@
+//We are basically storing sum%k and storing it in the hashmap and checking it.
+//Math logic is that the overall sum will get cancelled out because of modulo
+
+class Solution {
+    public boolean checkSubarraySum(int[] nums, int k) {
+        HashMap<Integer, Integer> map = new HashMap<>();
+        map.put(0, -1);
+        int sum = 0;
+        for (int i = 0; i<nums.length; i++) {
+            sum += nums[i];
+            int rem = sum%k;
+            if (map.containsKey(rem)) 
+                if (i - map.get(rem)>=2) 
+                    return true;
+            if (!map.containsKey(rem)) 
+                map.put(rem, i);
+        }
+        return false;
+    }
+}