solution.md

# 猜字母

把abcd...s共19个字母组成的序列重复拼接106次，得到长度为2014的串。  
接下来删除第1个字母（即开头的字母a），以及第3个，第5个等所有奇数位置的字母。   
得到的新串再进行删除奇数位置字母的动作。如此下去，最后只剩下一个字母，请写出该字母。  

以下程序哪项运行后不能得到正确答案？

## aop

### before

```cpp
#include <bits/stdc++.h>
using namespace std;
```
### after

```cpp

```

## 答案

```cpp
int a[2014];
int main()
{
    int count = 2014;
    for (int i = 0; i < 2014; i++)
    {
        a[i] = i + 1;
    }
    do
    {
        for (int i = 0; i <= count - 1; i += 2)
            a[i] = 0;
        count = 0;
        for (int j = 0; j <= 2013; j++)
        {
            if (a[j] != 0)
            {
                a[count] = a[j];
                a[j] = 0;
                count++;
            }
        }
    } while (count != 1);
    cout << char('a' + (a[0] % 19));
    return 0;
}
```
## 选项


### A

```cpp
int main()
{
    string s = "abcdefghijklmnopqrs";
    string str;

    for (int i = 0; i < 106; i++)
    {
        str += s;
    }

    while (str.length() > 1)
    {
        for (int i = 0; i < str.length(); i++)
        {
            str.erase(i, 1);
        }
    }
    cout << str;
    return 0;
}
```

### B

```cpp
int main()
{
    char a[2015];
    int t = 0;
    for (int j = 0; j < 106; j++)
        for (int i = 0; i < 19; i++)
            a[t++] = 'a' + i;
    a[t] = 0;
    int k;
    while (t != 1)
    {
        k = 0;
        for (int j = 1; j < t; j += 2)
            a[k++] = a[j];
        a[k] = '\0';
        t = k;
    }
    cout << a << endl;
    return 0;
}
```

### C

```cpp
int main()
{
    vector<char> vc1;
    int i;
    for (i = 0; i < 2014; i++)
        vc1.push_back('a' + (i % 19));
    while (vc1.size() != 1)
    {
        vector<char> vc2;

        for (i = 1; i < vc1.size(); i += 2)
            vc2.push_back(vc1[i]);
        vc1.assign(vc2.begin(), vc2.end());
    }
    cout << vc1[0] << endl;
    return 0;
}
```