1525. Number of Good Ways to Split a String LeetCode Solution

In this guide, you will get 1525. Number of Good Ways to Split a String LeetCode Solution with the best time and space complexity. The solution to Number of Good Ways to Split a String problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Problem Statement
Complexity Analysis
Number of Good Ways to Split a String solution in C++
Number of Good Ways to Split a String solution in Java
Number of Good Ways to Split a String solution in Python
Additional Resources

1525. Number of Good Ways to Split a String LeetCode Solution image

Problem Statement of Number of Good Ways to Split a String

You are given a string s.
A split is called good if you can split s into two non-empty strings sleft and sright where their concatenation is equal to s (i.e., sleft + sright = s) and the number of distinct letters in sleft and sright is the same.
Return the number of good splits you can make in s.

Example 1:

Input: s = “aacaba”
Output: 2
Explanation: There are 5 ways to split “aacaba” and 2 of them are good.
(“a”, “acaba”) Left string and right string contains 1 and 3 different letters respectively.
(“aa”, “caba”) Left string and right string contains 1 and 3 different letters respectively.
(“aac”, “aba”) Left string and right string contains 2 and 2 different letters respectively (good split).
(“aaca”, “ba”) Left string and right string contains 2 and 2 different letters respectively (good split).
(“aacab”, “a”) Left string and right string contains 3 and 1 different letters respectively.

Example 2:

Input: s = “abcd”
Output: 1
Explanation: Split the string as follows (“ab”, “cd”).

Constraints:

1 <= s.length <= 105
s consists of only lowercase English letters.

Complexity Analysis

Time Complexity: O(n)
Space Complexity: O(n)

1525. Number of Good Ways to Split a String LeetCode Solution in C++

class Solution {
 public:
  int numSplits(string s) {
    const int n = s.length();
    int ans = 0;
    // prefix[i] := the number of unique letters in s[0..i]
    vector<int> prefix(n);
    // suffix[i] := of unique letters in s[i..n)
    vector<int> suffix(n);
    unordered_set<int> seen;

    for (int i = 0; i < n; ++i) {
      seen.insert(s[i]);
      prefix[i] = seen.size();
    }

    seen.clear();

    for (int i = n - 1; i >= 0; --i) {
      seen.insert(s[i]);
      suffix[i] = seen.size();
    }

    for (int i = 0; i + 1 < n; ++i)
      if (prefix[i] == suffix[i + 1])
        ++ans;

    return ans;
  }
};
/* code provided by PROGIEZ */

1525. Number of Good Ways to Split a String LeetCode Solution in Java

class Solution {
  public int numSplits(String s) {
    final int n = s.length();
    int ans = 0;
    int[] prefix = new int[n];
    int[] suffix = new int[n];
    Set<Character> seen = new HashSet<>();

    for (int i = 0; i < n; ++i) {
      seen.add(s.charAt(i));
      prefix[i] = seen.size();
    }

    seen.clear();

    for (int i = n - 1; i >= 0; --i) {
      seen.add(s.charAt(i));
      suffix[i] = seen.size();
    }

    for (int i = 0; i + 1 < n; ++i)
      if (prefix[i] == suffix[i + 1])
        ++ans;

    return ans;
  }
}
// code provided by PROGIEZ

1525. Number of Good Ways to Split a String LeetCode Solution in Python

class Solution:
  def numSplits(self, s: str) -> int:
    n = len(s)
    ans = 0
    seen = set()
    prefix = [0] * n
    suffix = [0] * n

    for i in range(n):
      seen.add(s[i])
      prefix[i] = len(seen)

    seen.clear()

    for i in reversed(range(n)):
      seen.add(s[i])
      suffix[i] = len(seen)

    for i in range(n - 1):
      if prefix[i] == suffix[i + 1]:
        ans += 1

    return ans
 # code by PROGIEZ