g0001_0100.s0022_generate_parentheses.Solution.kt Maven / Gradle / Ivy
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Kotlin-based LeetCode algorithm problem solutions, regularly updated
package g0001_0100.s0022_generate_parentheses
// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Dynamic_Programming
// #Backtracking #Algorithm_II_Day_11_Recursion_Backtracking #Udemy_Backtracking/Recursion
// #2022_03_29_Time_210_ms_(78.51%)_Space_37.3_MB_(76.72%)
class Solution {
fun generateParenthesis(n: Int): List {
val sb = StringBuilder()
val ans: MutableList = ArrayList()
return generate(sb, ans, n, n)
}
private fun generate(sb: StringBuilder, str: MutableList, open: Int, close: Int): List {
if (open == 0 && close == 0) {
str.add(sb.toString())
return str
}
if (open > 0) {
sb.append('(')
generate(sb, str, open - 1, close)
sb.deleteCharAt(sb.length - 1)
}
if (close > 0 && open < close) {
sb.append(')')
generate(sb, str, open, close - 1)
sb.deleteCharAt(sb.length - 1)
}
return str
}
}