Excel Sheet Column Title

char *convertToTitle(int n) {
    char num[20];int k = 0;
    while(n){
        num[k++] = (n-1)%26 + 'A';
        n = (n-1)/26;
    }
    for(int i = 0;i < k /2; i++){
            char temp = num[i];
                 num[i] = num[k-i-1];
                 num[k-i-1] = temp;
    }
    num[k] = '';
    return num;
}

写的比较挫，本质就是没有0的二进制~