Problem p02937 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>

using namespace std;

#define INF 1001000100010001000
#define MOD 1000000007
#define EPS 1e-10
#define int long long
#define rep(i, N) for (int i = 0; i < N; i++)
#define Rep(i, N) for (int i = 1; i < N; i++)
#define For(i, a, b) for (int i = (a); i < (b); i++)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define pii pair<int, int>
#define vi vector<int>
#define vvi vector<vi>
#define vb vector<bool>
#define vvb vector<vb>
#define vp vector<pii>
#define all(a) (a).begin(), (a).end()
#define Int(x)                                                                 \
  int x;                                                                       \
  cin >> x;
#define int2(x, y)                                                             \
  Int(x);                                                                      \
  Int(y);
#define int3(x, y, z)                                                          \
  Int(x);                                                                      \
  int2(y, z);
#define in(x, a, b) ((a) <= (x) && (x) < (b))
#define fir first
#define sec second
#define ffir first.first
#define fsec first.second
#define sfir second.first
#define ssec second.second
#define Decimal fixed << setprecision(10)

// int dxy[5] = {0, 1, 0, -1, 0};
//  cmd

signed main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  string input;
  cin >> input;
  string target;
  cin >> target;

  vvi table(input.size(), vi(30, -1));

  {
    vi tmp(30, -1);
    for (int i = input.size() - 1; i >= 0; i--) {
      tmp[input[i] - 'a'] = i;
      rep(j, table[i].size()) {
        if (table[i][j] == -1)
          table[i][j] = tmp[j];
      }
    }
    for (int i = input.size() - 1; i >= 0; i--) {
      tmp[input[i] - 'a'] = i;
      rep(j, table[i].size()) {
        if (table[i][j] == -1)
          table[i][j] = tmp[j];
      }
    }
  }

  int ans = 0, cnt = 0;
  rep(i, target.size()) {
    int tmp = table[ans][target[i] - 'a'];
    if (tmp == -1) {
      std::cout << -1 << std::endl;
      return 0;
    } else {
      if (ans > tmp) {
        cnt++;
      }
      ans = tmp + 1;
    }
  }

  cout << cnt * input.size() + ans << endl;

  return 0;
}


Fixed submission:
#include <bits/stdc++.h>

using namespace std;

#define INF 1001000100010001000
#define MOD 1000000007
#define EPS 1e-10
#define int long long
#define rep(i, N) for (int i = 0; i < N; i++)
#define Rep(i, N) for (int i = 1; i < N; i++)
#define For(i, a, b) for (int i = (a); i < (b); i++)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define pii pair<int, int>
#define vi vector<int>
#define vvi vector<vi>
#define vb vector<bool>
#define vvb vector<vb>
#define vp vector<pii>
#define all(a) (a).begin(), (a).end()
#define Int(x)                                                                 \
  int x;                                                                       \
  cin >> x;
#define int2(x, y)                                                             \
  Int(x);                                                                      \
  Int(y);
#define int3(x, y, z)                                                          \
  Int(x);                                                                      \
  int2(y, z);
#define in(x, a, b) ((a) <= (x) && (x) < (b))
#define fir first
#define sec second
#define ffir first.first
#define fsec first.second
#define sfir second.first
#define ssec second.second
#define Decimal fixed << setprecision(10)

// int dxy[5] = {0, 1, 0, -1, 0};
//  cmd

signed main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  string input;
  cin >> input;
  string target;
  cin >> target;

  vvi table(input.size(), vi(30, -1));

  {
    vi tmp(30, -1);
    for (int i = input.size() - 1; i >= 0; i--) {
      tmp[input[i] - 'a'] = i;
      rep(j, table[i].size()) {
        if (table[i][j] == -1)
          table[i][j] = tmp[j];
      }
    }
    for (int i = input.size() - 1; i >= 0; i--) {
      tmp[input[i] - 'a'] = i;
      rep(j, table[i].size()) {
        if (table[i][j] == -1)
          table[i][j] = tmp[j];
      }
    }
  }

  int ans = 0, cnt = 0;
  rep(i, target.size()) {
    int tmp = table[ans][target[i] - 'a'];
    if (tmp == -1) {
      std::cout << -1 << std::endl;
      return 0;
    } else {
      if (ans > tmp) {
        cnt++;
      }
      ans = tmp + 1;
      if (ans == input.size()) {
        ans = 0;
        cnt++;
      }
    }
  }

  cout << cnt * input.size() + ans << endl;

  return 0;
}