import java.util.*;
public class Solution {
/**
*
* @param s string字符串
* @return bool布尔型
*/
public boolean isValid (String s) {
Stack<Character> stack = new Stack<>();
Map<Character, Character> map = new HashMap<>();
map.put(')', '(');
map.put(']', '[');
map.put('}', '{');
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
Character l = map.get(c);
if(l!=null){
if(stack.isEmpty() || stack.pop() != l){
return false;
}
} else {
stack.push(c);
}
}
return stack.isEmpty();
}
}