You are given a string s, a split is called good if you can split s into 2 non-empty strings p and q where its concatenation is equal to s and the number of distinct letters in p and q are 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").
Example 3:
Input: s = "aaaaa"
Output: 4
Explanation: All possible splits are good.
Example 4:
Input: s = "acbadbaada"
Output: 2
Constraints:
s contains only lowercase English letters.
1 <= s.length <= 10^5
class Solution {
public int numSplits(String s) {
int[] leftCount = new int[26];
int[] rightCount = new int[26];
int leftUnique = 0, rightUnique = 0;
for (char c : s.toCharArray()) {
if (rightCount[c - 'a'] == 0)
rightUnique++;
rightCount[c - 'a']++;
}
int ans = 0;
for (char c : s.toCharArray()) {
if (leftCount[c - 'a'] == 0)
leftUnique++;
if (rightCount[c - 'a'] == 1)
rightUnique--;
rightCount[c - 'a']--;
leftCount[c - 'a']++;
if (leftUnique == rightUnique)
ans++;
}
return ans;
}
}