My program works with tests like this:

4

0 00 0

10 11

And my program give right answers but WA#1. That my code, whats wrong??

#include <bits/stdc++.h>

using namespace std;

int n;
string ans,q;

int main()
{
    cin >> n;

    while (!cin.eof()) {                                     //while not eof reading
        getline(cin,q);                                      //read 1 line
        ans = "";

        for (int i = 0; i < q.length(); i++)                 //remove all except 0 and 1
            if (q[i] == '0' || q[i] == '1')
                ans += q[i];


        if (ans.length() < n-1 || ans.length() > n+1)         //if its empty continue
            continue;

        int pos_sum = 0;

        for (int i = 0; i < ans.length(); i++) {              //count sum of positions
            if (ans[i] == '1') {
                pos_sum += i+1;
            }
        }

        if (ans.length() > n) {                              //if there 1 unnecessary element check all
            bool fg = false;                                 //elements and remove him

            for (int i = 0; i < ans.length(); i++) {
                int loc_pos_sum = 0;

                if (fg) {
                    cout << ans[i];
                    continue;
                }

                for (int j = 0; j < ans.length(); j++) {
                    if (j == i)
                        continue;

                    if (ans[j] == '1')
                        loc_pos_sum += j+1 - int(j >= i);
                }

                if (loc_pos_sum % (n+1) == 0) {
                    fg = true;
                } else {
                    cout << ans[i];
                }
            }
        } else if (ans.length() < n) {                                 //if there 1 removed element
            bool fg = false;                                           //check all positions for him

            for (int i = 0; i <= ans.length(); i++) {
                int loc_pos_sum = 0;

                if (fg) {
                    cout << ans[i];
                    continue;
                }

                for (int j = 0; j < ans.length(); j++) {
                    if (ans[j] == '1') {
                        loc_pos_sum += j+1 + int(j >= i);
                    }
                }

                if (loc_pos_sum % (n+1) == 0) {
                    cout << 0;
                    fg = true;
                }

                if ((i+1+loc_pos_sum) % (n+1) == 0) {
                    cout << 1;
                    fg = true;
                }

                cout << ans[i];
            }
        } else {                                                          //if '0' replaced to '1' check all
            bool fg = false;                                              //elements and replace
            for (int i = 0; i < ans.length(); i++) {
                if (ans[i] == '1' && (pos_sum-i-1)%(n+1) == 0 && !fg) {
                    cout << 0;
                    fg = true;
                } else {
                    cout << ans[i];
                }
            }
        }

        cout << "\n";
    }
    return 0;
}

Edited by author 30.10.2018 16:07