hardCombinatoricsDynamic ProgrammingMathString 0 views

Count Number of Balanced Permutations

You are given a string num.

You are given a string num. A string of digits is called balanced if the sum of the digits at even indices is equal to the sum of the digits at odd indices.

Return the number of distinct permutations of num that are balanced.

Since the answer may be very large, return it modulo 10^9 + 7.

A permutation is a rearrangement of all the characters of a string.

Count Number of Balanced Permutations diagram

Example 1

Input: num = "123"

Output: 2

Example 2

Input: num = "112"

Output: 1

Example 3

Input: num = "12345"

Output: 0

Constraints

  • 2 <= num.length <= 80
  • num consists of digits '0' to '9' only.

Hints

Companies

No companies reported yet.

Discussion

Sign in to join the discussion.

Loading discussion...

Test results

No test cases yet.