使用两个数组分别记录字符和对应的数字，然后清除原来的vector，重新向里面添加元素。注意判断1个字符时，不将'1'加入vector。

int compress(vector
     
      & chars) {    const int N = 1000;    char words[N];//存储字符    int count[N];//存储数字    memset(words, ' ', sizeof(words));//count初始化为全' '    memset(count, 0, sizeof(count));//count初始化为全0    char lastChar = ' ';//ASCII:32        int i = 0;    for (auto c : chars)    {        if (c != lastChar)//新字符        {            if (lastChar == ' ')            {                i = 0;            }            else            {                i++;            }        }        words[i] = c;        count[i]++;        lastChar = c;    }    chars.clear();    for (int j = 0; j <= i; j++)    {        chars.push_back(words[j]);        int a = count[j];        if (a == 1)        {            continue;        }        char str[4];        sprintf(str, "%d", a);        for (auto s : str)        {            if (s == '\0')            {                break;            }            chars.push_back(s);        }    }    int sum = chars.size();    return sum;}