https://www.spoj.com/problems/JULKA/

JULKA.cpp

////https://www.spoj.com/problems/JULKA/
#include <iostream>
#include <cstring>
using namespace std;
int main()
{
    int t=10;
    int size = 105;
    while (t--)
    {
        char app_together[size], app_more[size], app_together_untouched[size];
        cin>>app_together;
        cin>>app_more;

        for(int i=0; i<size; i++)
        {
            app_together_untouched[i] = app_together[i];
        }

        int len_app_together = strlen(app_together);
        int len_app_more = strlen(app_more);

        char ans[size];
        ans[len_app_together] = '\0';
        int flag = 1;
        for (int i=len_app_together-1; i>=0; i--)
        {
            if (flag)
            {
                for (int j=len_app_more-1; j>=0; j--)
                {
                    char a = app_together[i];
                    char b = app_more[j];
                    if(a >= b)
                    {
                        ans[i] = 48 + a - b;
                    }
                    if(a < b)
                    {
                        ans[i] = 48 + (10 + a - b);
                        app_together[i-1] -= 1;
                    }
                    i--;
                }
            }
            flag = 0;
            /*CAUTION: Index may get out of bounds here when i=-1*/
            if (i>-1 && (int)app_together[i] + 1 == 48)
            {
                ans[i] = app_together[i] + 10;
                app_together[i-1] -= 1;
            }
            if (i>-1 && (int)app_together[i] >= 48)
            {
                ans[i] = app_together[i];
            }
        }
        int len_ans = strlen(ans);

        //Finding the final answer for Natalia below by diving ans by 2.

        char final_ans[size];
        final_ans[len_ans] = '\0';
        int next_step_add = 0;
        for (int i=0 ; i < len_ans; i++)
        {
            int x = ans[i];
            x = x-48+next_step_add;
            if(x>=2)
            {
                if (x%2 == 0)
                {
                    final_ans[i] = x/2 + 48;
                    next_step_add = 0;
                }
                else
                {
                    final_ans[i] = x/2 + 48;
                    next_step_add=10;
                    continue;
                }
            }
            else
            {
                final_ans[i] = x/2 + 48;
                if (x%2 == 0)
                {
                    next_step_add = 0;
                }
                else
                {
                    next_step_add = 10;
                }
            }
        }

        int len_final_ans = strlen(final_ans);
        char final_ans_mod[size];
        int flag_for_zeros_before_num = 1;
        int counter =0;
        for(int i=0; i<=len_final_ans; i++)
        {
            if (final_ans[i] == '0' && flag_for_zeros_before_num)
            {
                counter++;
                continue;
            }
            else
            {
                final_ans_mod[i-counter] = final_ans[i];
                flag_for_zeros_before_num = 0;
            }
        }
        /*Above I've saved Final Answer for natalia in final_ans_mod. Later, in the last line I'll print it*/

        //Finding the final answer for Klaudia below by subtracting natalias ans from app_together.

        char final_ans_klaudia[size];

        int len_final_ans_mod = strlen(final_ans_mod);
        int len_app_together_untouched = strlen(app_together_untouched);

        final_ans_klaudia[len_app_together_untouched] = '\0';
        flag = 1;
        for (int i=len_app_together_untouched-1; i>=0; i--)
        {
            if (flag)
            {
                for (int j=len_final_ans_mod-1; j>=0; j--)
                {
                    char a = app_together_untouched[i];
                    char b = final_ans_mod[j];
                    if(a >= b)
                    {
                        final_ans_klaudia[i] = 48 + a - b;
                    }
                    if(a < b)
                    {
                        final_ans_klaudia[i] = 48 + (10 + a - b);
                        app_together_untouched[i-1] -= 1;
                    }
                    i--;
                }
            }
            flag = 0;
            if (i>-1 && (int)app_together_untouched[i] + 1 == 48)
            {
                final_ans_klaudia[i] = app_together[i] + 10;
                app_together_untouched[i-1] -= 1;
            }
            if (i>-1 && (int)app_together_untouched[i] >= 48)
            {
                final_ans_klaudia[i] = app_together_untouched[i];
            }
        }

        int len_final_ans_klaudia = strlen(final_ans_klaudia);
        char final_ans_klaudia_mod[size];
        flag_for_zeros_before_num = 1;
        counter = 0;
        for(int i=0; i<=len_final_ans_klaudia; i++)
        {
            if (final_ans_klaudia[i] == '0' && flag_for_zeros_before_num)
            {
                counter++;
                continue;
            }
            else
            {
                final_ans_klaudia_mod[i-counter] = final_ans_klaudia[i];
                flag_for_zeros_before_num = 0;
            }
        }
        cout<<final_ans_klaudia_mod<<"\n";
        cout<<final_ans_mod<<"\n";
    }
    return 0;
}

https://gist.github.com/garganshul108/b82e137099c1db7726d044e95f802800