【LeetCode】【Kotlin】20. Valid Parentheses (stack (使用MutableList))

 

1. class Solution {
2. fun isValid(s: String): Boolean {
3. var stack : MutableList<Char> = mutableListOf()
4. for (char in s){
5. if(char == '}' || char == ')' || char == ']'){
6. val popedStack = if(stack.size > 0){
7. stack.removeAt(stack.size-1)
8. }else{
9. 'x'
10. }
11. when(char){
12. '}' -> if(popedStack != '{') return false
13. ')' -> if(popedStack != '(') return false
14. ']' -> if(popedStack != '[') return false
15. }
16. }else{
17. stack.add(char)
18. }
19. }
20. return stack.size == 0
21. }
22. }

注意 : "[(])"的輸出結果是false。但"[()]"為true。

(用時45分鐘)