字符串解码

题目

思路

• 有限状态机

代码

class Solution {
    public String decodeString(String s) {
        char[] chars = s.toCharArray();
        int len = chars.length;
        Stack<String> strs = new Stack<>();
        Stack<Integer> nums = new Stack<>();
        int num = 0;
        String str = "";
        for (int i = 0; i < len; i++) {
            //计算数字
            if (chars[i] >= '0' && chars[i] <= '9') {
                num = num * 10 + (chars[i] - '0');
            //对左括号入栈
            } else if (chars[i] == '[') {
                nums.push(num);
                strs.push(str);
                num = 0;
                str = "";
            //对右括号入栈
            } else if (chars[i] == ']') {
                StringBuilder temp = new StringBuilder(str);
                int size = nums.pop();
                for (int j = 1; j < size; j++) {
                    temp.append(str);
                }
                str = strs.pop() + temp.toString();
            //对字符串相加即可
            } else {
                str += chars[i];
            }
        }
        return str;
    }
}

字符串解码