数组中字符串的最大值

The value of an alphanumeric string can be defined as:

• The numeric representation of the string in base 10, if it comprises of digits only.
• The length of the string, otherwise.

Given an array strs of alphanumeric strings, return the maximum value of any string in strs.

 

Example 1:

Input: strs = ["alic3","bob","3","4","00000"]
Output: 5
Explanation: 
- "alic3" consists of both letters and digits, so its value is its length, i.e. 5.
- "bob" consists only of letters, so its value is also its length, i.e. 3.
- "3" consists only of digits, so its value is its numeric equivalent, i.e. 3.
- "4" also consists only of digits, so its value is 4.
- "00000" consists only of digits, so its value is 0.
Hence, the maximum value is 5, of "alic3".

Example 2:

Input: strs = ["1","01","001","0001"]
Output: 1
Explanation: 
Each string in the array has value 1. Hence, we return 1.

 

Constraints:

• 1 <= strs.length <= 100
• 1 <= strs[i].length <= 9
• strs[i] consists of only lowercase English letters and digits.

/*
 * 思路：
 * 使用Java Stream API进行处理。首先将字符串数组转换为Stream，对每一个字符串判断其是否只包含数字。
 * 如果是，则转换为整数；否则，转换为字符串的长度。最后使用Stream的max方法找到最大值。
 */
import java.util.Arrays;

public class Solution {
    public int maximumValue(String[] strs) {
        return Arrays.stream(strs)
                .mapToInt(str -> str.matches("\\d+") ? Integer.parseInt(str) : str.length())
                .max()
                .orElse(0);
    }
}

此题解采用了遍历数组的方法，对每个字符串进行判断和处理。具体步骤如下：\n1. 初始化一个变量 `maxnum` 用于存储最大值，初始为0。\n2. 遍历字符串数组 `strs` 中的每一个字符串。\n3. 对于每个字符串，判断其是否只包含数字（使用 `isdigit()` 方法）。\n - 如果只包含数字，将其转换为整数，并与 `maxnum` 进行比较，更新 `maxnum`。\n - 如果包含字母，取其长度，并与 `maxnum` 进行比较，更新 `maxnum`。\n4. 遍历结束后，返回 `maxnum` 作为结果，即字符串数组中的最大值。

O(n)

O(1)