# PROBLEM LINK:

**Author:** Bhushan Khanale

**Tester:** D Teja Vardhan Reddy

**Editorialist:** Bhushan Khanale

# DIFFICULTY:

EASY

# PREREQUISITES:

Prefix array, hexadecimal number system.

# PROBLEM:

The problem asks you ti find number of alphabets you can get through hexadecimal

numbers in a given range [L, R].

# QUICK EXPLANATION:

The solution to the problem is very simple if you know about hexadecimal number

systems. You can read about it

here.

Then convert all numbers in the range to hexadecimal numbers and count the

number of alphabets you get. Use prefix array to answer all testcases.

# EXPLANATION:

First to convert decimal number into hexadecimal number you need to divide

the number by 16 (since this is base 16), and keep recording the remainder.

Here as we are only concerned about the alphabets, we need to count the

remainders which are \geq 10. This is because in hexadecimal number system

the alphabets represent the numbers in the range [10, 15]. Hence the decimal

numbers in that range will be represented by hexadecimal numbers [A, F].

Since there are mutiple testcases, we only need to calculate this once and use

prefix array which would keep count of total alphabets at every index. Then we

can process each query with O(1).

# AUTHOR’S AND TESTER’S SOLUTIONS:

Author’s solution can be found here.

Tester’s solution can be found here.