LeetCode in Kotlin
2351. First Letter to Appear Twice
Easy
Given a string s consisting of lowercase English letters, return the first letter to appear twice.
Note:
- A letter
aappears twice before another letterbif the second occurrence ofais before the second occurrence ofb. swill contain at least one letter that appears twice.
Example 1:
Input: s = “abccbaacz”
Output: “c”
Explanation:
The letter ‘a’ appears on the indexes 0, 5 and 6.
The letter ‘b’ appears on the indexes 1 and 4.
The letter ‘c’ appears on the indexes 2, 3 and 7.
The letter ‘z’ appears on the index 8.
The letter ‘c’ is the first letter to appear twice, because out of all the letters the index of its second occurrence is the smallest.
Example 2:
Input: s = “abcdd”
Output: “d”
Explanation:
The only letter that appears twice is ‘d’ so we return ‘d’.
Constraints:
2 <= s.length <= 100sconsists of lowercase English letters.shas at least one repeated letter.
Solution
class Solution {
fun repeatedCharacter(s: String): Char {
val n = s.length
val hm = IntArray(26)
for (i in 0 until n) {
val c = s[i]
hm[c.code - 'a'.code]++
if (hm[c.code - 'a'.code] > 1) {
return c
}
}
return '0'
}
}