LeetCode 20. Valid Parentheses
Considering with following cases "]" "{[}]"
class Solution { public boolean isValid(String s) { Stack<Character> stack = new Stack<>(); for (int i = 0; i < s.length(); i++){ char c = s.charAt(i); if (c == '(' || c == '[' || c == '{'){ stack.push(c); } else if (stack.size() == 0){ return false; } else if (c == ')' && stack.pop() != '('){ return false; } else if (c == ']' && stack.pop() != '['){ return false; } else if (c == '}' && stack.pop() != '{'){ return false; } } return stack.size() == 0; } }