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

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

Description

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

You can split strings 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:

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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:

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Input: s = "aba"
Output: 2

Explanation:

One way to split maximally is [‘a’, ‘ba’].

Example 3:

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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.

Hints/Notes

  • 2024/10/01
  • back tracking
  • No solution from 0x3F

Solution

Language: C++

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class Solution {
public:
    unordered_set<string> us;
    int res; string s_;
    int maxUniqueSplit(string s) {
        res = INT_MIN; s_ = s;
        dfs(0);
        return res;
    }

    void dfs(int index) {
        if (index == s_.size()) {
            res = max(res, (int)us.size());
            return;
        }
        for (int i = index + 1; i <= s_.size(); i++) {
            string tmp = s_.substr(index, i - index);
            if (!us.contains(tmp)) {
                us.insert(tmp);
                dfs(i);
                us.erase(tmp);
            }
        }
    }
};