C solution

int deletions_reqd = 0; int len_a = strlen(a); int len_b = strlen(b); int max = 0; int i = 0;

//printf("Running solution 2...\n");
int32_t alphabets_a[26] = {0};
int32_t alphabets_b[26] = {0};

max = ((len_a >= len_b) ? len_a : len_b);
//printf("max %i, len_a %i, len_b %i\n", max, len_a, len_b);

if(max == 0)
{
    goto end;
}

// accumulate repeated characters
for(i=0; i<max; i++)
{
    if(i < len_a)
    {
        //printf("array_a, %c, %u\n", a[i], (uint8_t)(a[i] - 'a'));
        alphabets_a[(a[i] - 'a')]++;
    }

    if(i < len_b)
    {
        alphabets_b[(b[i] - 'a')]++;
    }
}        

for(i=0; i<26; i++)
{
    //printf("%c: %u\n", ('a' + i), (uint8_t) alphabets_a[i]);
    if((alphabets_a[i] > 0) || (alphabets_b[i] > 0))
    {
        if(alphabets_a[i] == alphabets_b[i])
        {
            continue;
        }
        else 
        {
            deletions_reqd += abs((alphabets_a[i] - alphabets_b[i]));
        }
    }
}