Added 0303-range-sum-query-immutable.cpp

Signed-off-by: Al Asad Nur Riyad <[email protected]>

Author: nurRiyad

Diff for: cpp/0303-range-sum-query-immutable.cpp

@@ -0,0 +1,40 @@
+/*
+Given an integer array nums, handle multiple queries of the following type:
+
+Calculate the sum of the elements of nums between indices left and right inclusive where left <= right.
+
+Implement the NumArray class:
+
+  - NumArray(int[] nums) Initializes the object with the integer array nums.
+  - int sumRange(int left, int right) Returns the sum of the elements of nums between indices left and right 
+    inclusive (i.e. nums[left] + nums[left + 1] + ... + nums[right]).
+
+*/
+
+
+class NumArray {
+public:
+    vector<int> prefixSum;
+    NumArray(vector<int>& nums) {
+        int count=0;
+        for(int i=0;i<nums.size();i++){
+            count+=nums[i];
+            prefixSum.push_back(count);
+        }
+    }
+    
+    int sumRange(int left, int right) {
+        int answer=prefixSum[right];
+
+        if(left-1>=0){
+            answer-=prefixSum[left-1];
+        }
+        return answer;
+    }
+};
+
+/**
+ * Your NumArray object will be instantiated and called as such:
+ * NumArray* obj = new NumArray(nums);
+ * int param_1 = obj->sumRange(left,right);
+ */