有效的括号序列

'(', ')'

'{'

'}'

'['

']'

"()"

"()[]{}"

"([)]"

public class Solution {
/**
* @param s A string
* @return whether the string is a valid parentheses
*/
public boolean isValidParentheses(String s) {
// Write your code here
Stack<Integer> stk = new Stack<Integer>();
for(int i = 0;i < s.length();++i){
int pos = "(){}[]".indexOf(s.substring(i,i+1));
if(pos%2 == 1){
if(stk.isEmpty()||stk.pop()!= pos-1)
return false;
}else {
stk.push(pos);
}
}
return stk.isEmpty();
}
}