LeetCode 20. Valid Parentheses--验证括号是否有效

'('

')'

'{'

'}'

'['

']'

"()"

"()[]{}"

"(]"

"([)]"

import java.util.Stack;

public class Main {

public boolean isValid(String s) {
int n = s.length();
Stack<Character> stack = new Stack<Character>();
char[] c = s.toCharArray();
for (int i = 0; i < n; i++) {
if (c[i] == '(') {
stack.push(')');
} else if (c[i] == '[') {
stack.push(']');
} else if (c[i] == '{') {
stack.push('}');
} else if (stack.isEmpty() || stack.pop() != c[i]) {//pop是返回栈顶元素，并且删除栈顶元素
return false;
}
}//for
return stack.isEmpty();
}//isValid

public static void main(String[] args) {
//        System.out.println(new Main().isValid("{[()]}"));//true
System.out.println(new Main().isValid("{"));//false
}
}