【重点!!!】【栈】394.字符串解码

题目

法1：基于栈

class Solution {
   
    public String decodeString(String s) {
   
        int multi = 0, i = 0;
        StringBuilder res = new StringBuilder();
        LinkedList<Integer> multiStack = new LinkedList<>();
        LinkedList<String> stringStack = new LinkedList<>();
        while (i < s.length()) {
   
            char c = s.charAt(i);
            if (c == '[') {
   
                multiStack.offerLast(multi);
                stringStack.offerLast(res.toString());
                multi = 0;
                res = new StringBuilder();
            } else if (c == ']') {
   
                StringBuilder tmpBuilder = new StringBuilder();
                int tmpMulti = multiStack.removeLast();
                for (int j = 0; j < tmpMulti; ++j) {
   
                    tmpBuilder.append(res);
                }
                res = new StringBuilder(stringStack.removeLast() + tmpBuilder.toString());
            } else if (c >= '0' && c <= '9') {
   
                multi = 10 * multi + c - '0';
            } else {
   
                res.append(c);
            }
            ++i;
        }

        return res.toString();
    }
}