1593. Split a String Into the Max Number of Unique Substrings

Description

Given a string s, return the maximum number of unique substrings that the given string can be split into.

You can split string s into any list of non-empty substrings, where the concatenation of the substrings forms the original string. However, you must split the substrings such that all of them are unique.

A substring is a contiguous sequence of characters within a string.

 

Example 1:

Input: s = "ababccc"
Output: 5
Explanation: One way to split maximally is ['a', 'b', 'ab', 'c', 'cc']. Splitting like ['a', 'b', 'a', 'b', 'c', 'cc'] is not valid as you have 'a' and 'b' multiple times.

Example 2:

Input: s = "aba"
Output: 2
Explanation: One way to split maximally is ['a', 'ba'].

Example 3:

Input: s = "aa"
Output: 1
Explanation: It is impossible to split the string any further.

 

Constraints:

• 1 <= s.length <= 16

• s contains only lower case English letters.

 

Solutions

Solution: Backtracking

• Time complexity: O(n)
• Space complexity: O(n)

 

JavaScript

/**
 * @param {string} s
 * @return {number}
 */
const maxUniqueSplit = function (s) {
  const size = s.length;
  const uniqueSplit = new Set();
  let result = 0;

  backtracking();
  return result;

  function backtracking(start = 0) {
    if (start === size) {
      result = Math.max(uniqueSplit.size, result);
      return;
    }

    for (let index = start + 1; index <= size; index++) {
      const substring = s.slice(start, index);

      if (uniqueSplit.has(substring)) continue;
      uniqueSplit.add(substring);
      backtracking(index);
      uniqueSplit.delete(substring);
    }
  }
};