题目：

题解：

func compress(chars []byte) int {
    write, left := 0, 0
    for read, ch := range chars {
        if read == len(chars)-1 || ch != chars[read+1] {
            chars[write] = ch
            write++
            num := read - left + 1
            if num > 1 {
                anchor := write
                for ; num > 0; num /= 10 {
                    chars[write] = '0' + byte(num%10)
                    write++
                }
                s := chars[anchor:write]
                for i, n := 0, len(s); i < n/2; i++ {
                    s[i], s[n-1-i] = s[n-1-i], s[i]
                }
            }
            left = read + 1
        }
    }
    return write
}