题目：

题解：

void swap(char *a, char *b) {
    char t = *a;
    *a = *b, *b = t;
}

void reverse(char *a, char *b) {
    while (a < b) {
        swap(a++, --b);
    }
}

int compress(char *chars, int charsSize) {
    int write = 0, left = 0;
    for (int read = 0; read < charsSize; read++) {
        if (read == charsSize - 1 || chars[read] != chars[read + 1]) {
            chars[write++] = chars[read];
            int num = read - left + 1;
            if (num > 1) {
                int anchor = write;
                while (num > 0) {
                    chars[write++] = num % 10 + '0';
                    num /= 10;
                }
                reverse(&chars[anchor], &chars[write]);
            }
            left = read + 1;
        }
    }
    return write;
}