Count Inclusive-Band Sums of Nonempty Index Ranges
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: hard
Interview Round: Other
### Problem
Return the number of nonempty contiguous ranges whose sum lies between lower and upper inclusive. Count index ranges separately even when their sums are equal.
```cpp
int countRangeSum(vector<int>& nums, int lower, int upper);
```
### Examples
```text
nums = [1,-1,2], lower=0, upper=1 -> 3
nums = [0], lower=0, upper=0 -> 1
```
### Constraints
- Length is 1 through 100000; values span signed 32-bit.
- -100000 <= lower <= upper <= 100000.
- The final count is guaranteed to fit signed 32-bit.
Overview: Count Inclusive-Band Sums of Nonempty Index Ranges. Return the number of nonempty contiguous ranges whose sum lies between lower and upper inclusive. Count index ranges separately even when their sums are equal.
