Leetcode 1190

5.26的每日一题，需从内到外翻转字符串，我们可以遇到)就开始翻转内容

可以用stack来存储每个(的index，找到第一个)的时候即为优先级最高的里面，开始第一次翻转char[]数组

Sample input:"(abcd)" output:"dcba"

public String reverseParentheses(String s) {
    StringBuilder sb = new StringBuilder();//用stringbuilder构建字符串
    
    char[] chs = s.toCharArray();
    int n = s.length();
    Stack<Integer> stack = new Stack<>();

    for (int i = 0; i < n; i++) {
        if (chs[i] == '(') {//记录index
            stack.push(i);
        }

        if (chs[i] == ')') {//匹配，开始
            reverse(chs, stack.pop() + 1, i);
        }
    }

    for (int i = 0; i < n; i++) {
        if (chs[i] != '(' && chs[i] != ')') {
            sb.append(chs[i]);
        }
    }

    return sb.toString();
}

private void reverse(char[] chs, int low, int high) {
    while (low < high) {//左右双指针往中间交换char
        char temp = chs[low];
        chs[low++] = chs[high];
        chs[high--] = temp;
    }
}