Daily LeetCode – day0101 0816. Ambiguous Coordinates

import java.util.LinkedList;
import java.util.List;

// 0816. Ambiguous Coordinates
class Solution {
    public List<String> ambiguousCoordinates(String s) {
        List<String> ans = new LinkedList<>();
        int len = s.length();
        for (int mid = 2; mid < len - 1; ++mid) {
            List<String> leftNumbers = generateValidNumbers(s.substring(1, mid));
            List<String> rightNumbers = generateValidNumbers(s.substring(mid, len - 1));
            for (String leftNumber : leftNumbers) {
                for (String rightNumber : rightNumbers) {
                    StringBuilder sb = new StringBuilder();
                    sb.append('(').append(leftNumber).append(',').append(' ').append(rightNumber).append(')');
                    ans.add(sb.toString());
                }
            }
        }
        return ans;
    }

    private List<String> generateValidNumbers(String number) {
        int len = number.length();
        List<String> ret = new LinkedList<>();
        if (number.charAt(0) == '0') {
            if (len == 1) {
                ret.add("0");
                return ret;
            } else if (number.charAt(len - 1) != '0') {
                ret.add("0." + number.substring(1, len));
            }
        } else {
            ret.add(number);
            if (number.charAt(len - 1) != '0') {
                for (int i = 1; i < len; ++i) {
                    StringBuilder sb = new StringBuilder();
                    sb.append(number.substring(0, i)).append('.').append(number.substring(i, len));
                    ret.add(sb.toString());
                }
            }
        }
        return ret;
    }
}

学习笔记：
这是一道字符串的中等题，但我感觉已经挺复杂了。
首先是切分，切分完后左半段找出所有合法组合，右半段找出所有合法组合，然后拼起来。
最麻烦的就是前导零也就是第一位是0还有末尾多余0的情况。需要分类讨论。