g0301_0400.s0394_decode_string.Solution.kt Maven / Gradle / Ivy
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Kotlin-based LeetCode algorithm problem solutions, regularly updated
package g0301_0400.s0394_decode_string
// #Medium #Top_100_Liked_Questions #String #Stack #Recursion #Level_1_Day_14_Stack #Udemy_Strings
// #Big_O_Time_O(n)_Space_O(n) #2022_09_27_Time_224_ms_(64.86%)_Space_34.3_MB_(84.46%)
class Solution {
private var i = 0
fun decodeString(s: String): String {
var count = 0
val sb = StringBuilder()
while (i < s.length) {
val c = s[i]
i++
if (Character.isLetter(c)) {
sb.append(c)
} else if (Character.isDigit(c)) {
count = count * 10 + Character.getNumericValue(c)
} else if (c == ']') {
break
} else if (c == '[') {
// sub problem
val repeat = decodeString(s)
while (count > 0) {
sb.append(repeat)
count--
}
}
}
return sb.toString()
}
}