第一題：

#include <iostream>
#include <string>

using namespace std;

bool IsVoChar(char c)
{
    return (c == ‘a‘) || (c == ‘e‘) || (c == ‘o‘) || (c == ‘i‘) || (c == ‘u‘) ||
        (c == ‘A‘) || (c == ‘E‘) || (c == ‘O‘) || (c == ‘I‘) || (c == ‘U‘);
}

string reverseVoChar(string s)
{
    
 
int slen = s.length();
    for (int l = 0, r = slen - 1; l < r; ++l)
    {
        if (IsVoChar(s[l]))
        {
            while ((l < r) && !IsVoChar(s[r]))
                --r;

            swap(s[l], s[r--]);
        }
    }
    return s;
}

int main()
{
    string str1, str2;
    cin 
 
>> str1;

    str2 = reverseVoChar(str1);

    cout << str2 << endl;

    system("pause");
    return 0;
}

第二題：

第三題：

#include <iostream>
#include <sstream>

using namespace std;

string DelChar(string str)    //從字符串中提取出數字,剔除掉字母
{
    for (int i = 0; i < str.length();)
    {
        
 
int temp = (int)str[i];

        if (temp >= 48 && temp <= 57)
        {
            i++;
            continue;
        }
        else
        {
            str.erase(i, 1);
            continue;
        }
    }

    return str;
}

string DecToHex(string str)    //將字符串轉化為十六進制
{
    int i = 0;
    string result = "";
    i++;

    int n = 0;

    for (int i = str.length() - 1, j = 1; i >= 0; i--) 
    {
        n += (str[i] - ‘0‘) * j;
        j *= 10;
    }

    char _16[] = {
        ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘, ‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘
    };

    const int radix = 16;
    while (n) 
    {
        int i = n % radix;
        result = _16[i] + result;
        n /= radix;
    }

    return result;
}

int main()
{
    string str1, str2;
    cin >> str1;

    str1 = DelChar(str1);
    //cout << str1 << endl;

    str2 = DecToHex(str1);

    cout << str2 << endl;

    system("pause");
    return 0;
}

1.虎牙直播2019秋招編程題