diff --git a/src/main/java/com/thealgorithms/prefixsum/countof0and1.java b/src/main/java/com/thealgorithms/prefixsum/countof0and1.java
new file mode 100644
index 000000000000..ee753b592ff3
--- /dev/null
+++ b/src/main/java/com/thealgorithms/prefixsum/countof0and1.java
@@ -0,0 +1,25 @@
+import java.util.HashMap;
+
+public class countof0and1s {
+    // longest subarray with given equal number of 0's and 1's
+    public static void main(String[] args) {
+        HashMap<Integer,Integer> map = new HashMap<>();
+        int []arr = {0,1,0,1,1,1,0,0,1,0,1,0,0};
+        int presum = 0;
+        int res= Integer.MIN_VALUE;
+        for (int i = 0; i < arr.length ; i++)
+            if(arr[i]==0)
+                arr[i]=-1;
+        for (int right = 0; right < arr.length; right++) {
+            presum +=arr[right];
+            if(map.containsKey(presum))
+                res=Math.max(res,right- map.get(presum));
+            if(!map.containsKey(presum))
+                map.put(presum,right);
+            if (presum==0)
+                res = right+1;
+        }
+        System.out.println(res);
+
+    }
+}
\ No newline at end of file