diff --git a/E_303_RangeSumQueryImmutable.java b/E_303_RangeSumQueryImmutable.java
new file mode 100644
index 0000000..e4f94ec
--- /dev/null
+++ b/E_303_RangeSumQueryImmutable.java
@@ -0,0 +1,13 @@
+class NumArray {
+    int[] arr;
+    public NumArray(int[] nums) {
+        this.arr=new int[nums.length+1];
+        for(int i=1;i<arr.length;i++){
+            arr[i]=arr[i-1]+nums[i-1];
+        }
+    }
+    
+    public int sumRange(int left, int right) {
+            return arr[right+1]-arr[left];
+    }
+}
\ No newline at end of file