LeetCode20题不多说上代码

public boolean isValid(String s){
    Stack<Character> stack = new Stack<Character>();
    for (int i=0;i<s.length();i++){
        char c = s.charAt(i);
        if (c=='('||c=='['||c=='{')
            stack.push(c);
         else{
             //栈没字符匹配失败
             if (stack.isEmpty())
                 return false;
             char topChar = stack.pop();
             if (c==')'&&topChar!='(')
                 return false;
             if (c==']'&&topChar!='[')
                 return false;
             if (c=='}'&&topChar!='{')
                 return false;

    }}
    return stack.isEmpty();
}