Reverse String - Leet Code Solution
Problem Statement Write a function that reverses a string. The input string is…
October 04, 2020
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
Input: s = "ababccc"
Output: 5
Explanation: ['a', 'b', 'ab', 'c', 'cc']
Input: s = "aba"
Output: 2
Explanation: ['a', 'ba']
Example 3:
Input: s = "aa"
Output: 1
Explanation: It is impossible to split the string any further.
Problems like these are solved through recursions, where you want to extract a portion of string and repeat the same algorithm on the rest of string.
Lets look at the algorithm:
Lets look at one of example:
input=aba
a + (ba)
a + b + (a)
# a is duplicate, it will only (a, b)
Next iteration
ab + (a)
Next Iteration
aba + ()
Lets look at the code:
private int find(String s, Set<String> set) {
int max = 0;
for (int i=0; i<s.length(); i++) {
String sub = s.substring(0, i+1);
if (!set.contains(sub)) {
set.add(sub);
max = Math.max(max, 1 + find(s.substring(i+1), set));
set.remove(sub);
}
}
return max;
}
public int maxUniqueSplit(String s) {
Set<String> set = new HashSet<>();
return this.find(s, set);
}
Its O(n!)
, factorial of n.
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