Today I have done leetcode's October LeetCoding Challenge with cpp.

October LeetCoding Challenge 21

Description

Split a String Into the Max Number of Unique Substrings

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.

Solution

class Solution {
  int maxCount = 0;
  int len;
  unordered_set<string_view> sequences;
  void solve(int pos, int count, string &s) {
    if(len - pos < maxCount - count) return;
    if(pos >= len) {
      maxCount = max(maxCount, count);
      return;
    }
    for(int i = 0; i + pos < len; ++i) {
      string_view t(s.data() + pos, i + 1);
      if(sequences.count(t)) continue;
      sequences.insert(t);
      solve(pos + i + 1, count + 1, s);
      sequences.erase(t);
    }
  }
public:
  int maxUniqueSplit(string s) {
    len = s.length();
    solve(0, 0, s);
    return maxCount;
  }
};