Count Symmetric Integers
You are given two positive integers low and high.
An integer x consisting of 2 * n digits is symmetric if the sum of the first n digits of x is equal to the sum of the last n digits of x. Numbers with an odd number of digits are never symmetric.
Return the number of symmetric integers in the range [low, high].
Example 1
Input
low = 1, high = 100Output
9There are 9 symmetric integers between 1 and 100: 11, 22, 33, 44, 55, 66, 77, 88, and 99.
Example 2
Input
low = 1200, high = 1230Output
4There are 4 symmetric integers between 1200 and 1230: 1203, 1212, 1221, and 1230.
Constraints
- 1 <= low <= high <= 10^4