Create 0303-range-sum-query-immutable.ts

Author: D00NIK

Diff for: typescript/0303-range-sum-query-immutable.ts

@@ -0,0 +1,24 @@
+class NumArray {
+    prefix: number[] = [];
+
+    constructor(nums: number[]) {
+        let cur = 0;
+        for (const n of nums) {
+            cur += n;
+            this.prefix.push(cur);
+        }
+    }
+
+    sumRange(left: number, right: number): number {
+        const rightSum = this.prefix[right],
+            leftSum = (left > 0) ? this.prefix[left - 1] : 0;
+        
+        return rightSum - leftSum;
+    }
+}
+
+/**
+ * Your NumArray object will be instantiated and called as such:
+ * var obj = new NumArray(nums)
+ * var param_1 = obj.sumRange(left,right)
+ */