题解 | #在字符串中找出连续最长的数字串#

清晰！遍历一遍获取长度最大值+正则匹配判断，时间复杂度O(n)

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String string = sc.nextLine();
            doSearch(string);
        }
    }
    public static void doSearch(String string){
        int n = 0,maxOne = 0;//计数变量
        // 遍历一遍获取长度最大值，时间复杂度O(n)
        for(int i=0; i < string.length(); i++){
            if(Character.isDigit(string.charAt(i))){
                n++;
                maxOne = Integer.max(maxOne,n);
            }else{
                n = 0;
            }
        }
        // 再遍历一遍获取长度为最大值的子串，并判断子串中是否全是数字，时间复杂度O(n)
        StringBuilder sb = new StringBuilder(); 
        for(int i = 0; i <= string.length() - maxOne; i ++){
            String str = string.substring(i, i + maxOne);
            if(0 == str.replaceAll("[0-9]", "").length())){
                sb.append(str);
            }
        }
        System.out.println(sb+","+ maxOne);
    }
}