solves range sum query immutable

Author: anishLearnsToCode

src/RangeSumQueryImmutable.java

@@ -0,0 +1,16 @@
+public class RangeSumQueryImmutable {
+    private static class NumArray {
+        private final int[] result;
+
+        public NumArray(int[] array) {
+            result = new int[array.length + 1];
+            for (int index = 0 ; index < array.length ; index++) {
+                result[index + 1] = result[index] + array[index];
+            }
+        }
+
+        public int sumRange(int i, int j) {
+            return result[j] - result[i];
+        }
+    }
+}