每日OJ_牛客_OR59字符串中找出连续最长的数字串_双指针_C++_Java

目录

牛客_OR59字符串中找出连续最长的数字串

题目解析

C++代码1

C++代码2

C++代码3

Java代码

牛客_OR59字符串中找出连续最长的数字串

字符串中找出连续最长的数字串_牛客题霸_牛客网

题目解析

        双指针： 遍历整个字符串，遇到数字的时候，用双指针找出这段连续的数字子串，根据此时的长度更新起始位置和长度。

C++代码1

#include <iostream>
#include <string>
using namespace std;

int main()
{
    string s;
    cin >> s;
    int begin = -1, len = 0;
    for(int i = 0; i < s.size(); i++)
    {
        if(s[i] >= '0' && s[i] <= '9')
        {
            int j = i;
            while(j < s.size() && s[j] >= '0' && s[j] <= '9')
            {
                j++;
            }
            if(j - i > len)
            {
                begin = i;
                len = j - i;
            }
            i = j;
        }
    }
    if(begin == -1)
    {
        cout << "" << endl;
    }
    else
    {
        cout << s.substr(begin, len) << endl;
    }
    return 0;
}

C++代码2

#include <climits>
#include <iostream>
#include <string>
using namespace std;

int main()
{
    string str;
    cin >> str;
    int sz = str.size();
    int maxLen = 0;
    int begin = 0, end = 0;
    for(int left = 0, right = 0; left < sz && right < sz;)
    {
        while(left < sz && (str[left] > '9' || str[left] < '0')) // 是字母就循环
        {	// 或的两个没加括号直接数组越界。。。。
            ++left; // 找数字区间的左边
        }
        right = left;
        while(right < sz && str[right] >= '0' && str[right] <= '9') // 是数字就循环
        {
            ++right; // 找数字区间的右边
        }
        int len = right - left;
        // cout << "len : " << len << " " << left << " " << right << " sz " << sz << endl;
        if(len > maxLen && left < sz && right <= sz)
        {
            // string tmp(str.begin() + left, str.begin() + right);
            // cout << tmp << endl;
            // cout << left << " " << right << " sz " << sz << endl;
            end = right;
            begin = left;
            maxLen = len;
        }
        left = right;
    }
    string ret(str.begin() + begin, str.begin() + end);
    cout << ret << endl;
    return 0;
}

C++代码3

#include <iostream>
#include <cctype>
using namespace std;

int main() 
{
    string str, ret = "", tmp = "";
    cin >> str;
    int n = str.size();
    for(int i = 0; i <= n; i++)
    {
        if(isdigit(str[i]))
        {
            tmp += str[i]; // 进窗口
        }
        else
        {
            if(tmp.size() > ret.size())
            {
                ret = tmp;
            }
            else 
            {
                tmp = "";
            }
        }
    }
    cout << ret;
    return 0;
}

Java代码

import java.util.Scanner;
import java.io.*;
public class Main
{
    public static void main(String[] args) throws Exception
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        char[] s = br.readLine().toCharArray();
        int begin = 0, len = 0;
        for(int i = 0; i < s.length; i++)
        {
            if(s[i] >= '0' && s[i] <= '9')
            {
                int j = i;
                while(j < s.length && s[j] >= '0' && s[j] <= '9')
                {
                    j++;
                }
                if(j - i > len)
                {
                    begin = i;
                    len = j - i;
                }
                i = j;
            }
        }
        for(int i = begin; i < begin + len; i++)
        {
            System.out.print(s[i]);
        }
    }
}