LeetCode in Kotlin
1525. Number of Good Ways to Split a String
Medium
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 <= 105sconsists of only lowercase English letters.
Solution
class Solution {
fun numSplits(s: String): Int {
val hs = HashSet<Char>()
val dp1 = IntArray(s.length - 1)
val dp2 = IntArray(s.length - 1)
for (i in 0 until s.length - 1) {
val ch = s[i]
hs.add(ch)
dp1[i] = hs.size
}
val hm = HashSet<Char>()
for (i in s.length - 1 downTo 1) {
val ch = s[i]
hm.add(ch)
dp2[i - 1] = hm.size
}
var count = 0
for (i in 0 until s.length - 1) {
if (dp1[i] == dp2[i]) {
count++
}
}
return count
}
}