#include <bits/stdc++.h>  // {{{

// https://codeforces.com/blog/entry/96344

#pragma GCC optimize("O2,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

using namespace std;

using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
using d64 = double;
using d128 = long double;
template <typename T>
using vec = std::vector<T>;
template <typename T, size_t N>
using arr = std::array<T, N>;
template <typename T1, typename T2>
using pai = std::pair<T1, T2>;

template <typename T>
constexpr T MIN = std::numeric_limits<T>::min();

template <typename T>
constexpr T MAX = std::numeric_limits<T>::max();

template <typename T>
[[nodiscard]] static T sc(auto&& x) {
  return static_cast<T>(x);
}

template <typename T>
[[nodiscard]] static T sz(auto&& x) {
  return static_cast<T>(x.size());
}

static void NO() {
  std::cout << "NO\n";
}

static void YES() {
  std::cout << "YES\n";
}

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

#ifdef LOCAL
#define db(...) std::print(__VA_ARGS__)
#define dbln(...) std::println(__VA_ARGS__)
#else
#define db(...)
#define dbln(...)
#endif
//  }}}

void solve() {
  u32 n;
  cin >> n;

  string s;
  cin >> s;

  // NOTE: thought could loop thru the entire thing
  // knew memory was O(n^2), but didn't actually say:
  // ok what do i want to do - loop thru. this is impractical
  string prev(n, '1');
  // union_find<u64> uf;
  for (u32 i = 0; i < n; ++i) {
    if (i)
      s[i] = ('0' + 1 - (s[i] - '0'));
    s[i] = ('0' + 1 - (s[i] - '0'));
    cout << "i: " << i << endl;
    cout << s << endl;
  }
}

int main() {  // {{{
  cin.tie(nullptr)->sync_with_stdio(false);
  cin.exceptions(cin.failbit);

  int tc = 1;
  cin >> tc;

  for (int t = 0; t < tc; ++t) {
    solve();
  }

  return 0;
}
// }}}
