8. 字符串转换整数 (atoi) https://leetcode.cn/problems/string-to-integer-atoi
9. 回文数 https://leetcode.cn/problems/palindrome-number
50. Pow(x, n) https://leetcode.cn/problems/powx-n
67. 二进制求和 https://leetcode.cn/problems/add-binary
400. 第 N 位数字 https://leetcode.cn/problems/nth-digit
306. 累加数 https://leetcode.cn/problems/additive-number
842. 将数组拆分成斐波那契序列 https://leetcode.cn/problems/split-array-into-fibonacci-sequence
357. 计算各个位数不同的数字个数 https://leetcode.cn/problems/count-numbers-with-unique-digits
279. 完全平方数 https://leetcode.cn/problems/perfect-squares