Problem p03483 (C++)

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

//    #include <boost/multiprecision/cpp_int.hpp>
#define int long long
#define inf 1000000007
#define pa pair<int, int>
#define ll long long
#define pal pair<double, double>
#define ppap pair<pa, int>
#define PI 3.14159265358979323846
#define paa pair<int, char>
#define mp make_pair
#define pb push_back
#define EPS (1e-8)

int dx[8] = {0, 1, 0, -1, 1, 1, -1, -1};
int dy[8] = {1, 0, -1, 0, -1, 1, 1, -1};
using namespace std;
class pa3 {
public:
  int x;
  int y, z;
  pa3(int x = 0, int y = 0, int z = 0) : x(x), y(y), z(z) {}
  bool operator<(const pa3 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    return z < p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa3 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    return z > p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa3 &p) const {
    return x == p.x && y == p.y && z == p.z;
  }
  bool operator!=(const pa3 &p) const {
    return !(x == p.x && y == p.y && z == p.z);
  }
};

class pa4 {
public:
  int x;
  int y, z, w;
  pa4(int x = 0, int y = 0, int z = 0, int w = 0) : x(x), y(y), z(z), w(w) {}
  bool operator<(const pa4 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    if (z != p.z)
      return z < p.z;
    return w < p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa4 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    if (z != p.z)
      return z > p.z;
    return w > p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa4 &p) const {
    return x == p.x && y == p.y && z == p.z && w == p.w;
  }
};
class pa2 {
public:
  int x, y;
  pa2(int x = 0, int y = 0) : x(x), y(y) {}
  pa2 operator+(pa2 p) { return pa2(x + p.x, y + p.y); }
  pa2 operator-(pa2 p) { return pa2(x - p.x, y - p.y); }
  bool operator<(const pa2 &p) const { return y != p.y ? y < p.y : x < p.x; }
  bool operator>(const pa2 &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const pa2 &p) const {
    return abs(x - p.x) == 0 && abs(y - p.y) == 0;
  }
  bool operator!=(const pa2 &p) const {
    return !(abs(x - p.x) == 0 && abs(y - p.y) == 0);
  }
};

string itos(int i) {
  ostringstream s;
  s << i;
  return s.str();
}

int gcd(int v, int b) {
  if (v == 0)
    return b;
  if (b == 0)
    return v;
  if (v > b)
    return gcd(b, v);
  if (v == b)
    return b;
  if (b % v == 0)
    return v;
  return gcd(v, b % v);
}

int mod;
int extgcd(int a, int b, int &x, int &y) {
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  }
  int d = extgcd(b, a % b, y, x);
  y -= a / b * x;
  return d;
}
pa operator+(const pa &l, const pa &r) {
  return {l.first + r.first, l.second + r.second};
}
pa operator-(const pa &l, const pa &r) {
  return {l.first - r.first, l.second - r.second};
}

int pr[1000010];
int inv[1000010];

int beki(int wa, int rr, int warukazu) {
  if (rr == 0)
    return 1 % warukazu;
  if (rr == 1)
    return wa % warukazu;
  wa %= warukazu;
  if (rr % 2 == 1)
    return ((ll)beki(wa, rr - 1, warukazu) * (ll)wa) % warukazu;
  ll zx = beki(wa, rr / 2, warukazu);
  return (zx * zx) % warukazu;
}

int comb(int nn, int rr) {
  if (rr < 0 || rr > nn || nn < 0)
    return 0;
  int r = pr[nn] * inv[rr];
  r %= mod;
  r *= inv[nn - rr];
  r %= mod;
  return r;
}

void gya(int ert) {
  pr[0] = 1;
  for (int i = 1; i <= ert; i++) {
    pr[i] = (pr[i - 1] * i) % mod;
  }
  inv[ert] = beki(pr[ert], mod - 2, mod);
  for (int i = ert - 1; i >= 0; i--) {
    inv[i] = inv[i + 1] * (i + 1) % mod;
  }
}

//   cin.tie(0);
//	ios::sync_with_stdio(false);
// priority_queue<pa3,vector<pa3>,greater<pa3>> pq;
// sort(ve.begin(),ve.end(),greater<int>());
//   mt19937(clock_per_sec);
//  mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()) ;

//----------------kokomade tenpure------------

struct segsum {
  //       1
  //   2        3
  // 4   5   6    7

private:
public:
  // (1<<15)=32768
  // 1<<16 = 65536
  // 1<<17 = 131072
  // 1<<18 = 262144

  int cor = (1 << 18);

  vector<int> vec;
  vector<int> lazy;

  void shoki1() { vec.resize(2 * cor + 3, 0); }
  void shoki2() {
    for (int i = cor - 1; i > 0; i--)
      vec[i] = vec[2 * i] + vec[2 * i + 1];
  }
  void clear() {

    for (int i = 0; i < (int)vec.size(); i++)
      vec[i] = 0;
  }
  void updadd(int x, int w) {
    // x 項目に w加算
    x += cor;
    vec[x] += w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }

  void updchan(int x, int w) {
    // x項目をwに変更
    x += cor;
    vec[x] = w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }
  // [a,b)
  // k-th node
  // k no kukanha [l,r)
  int sum(int a, int b, int k = 1, int l = 0, int r = -10) {
    if (r < 0)
      r = cor;

    //	cout<<a<<" "<<b<<" "<<k<<" "<<l<<" "<<r<<endl;

    if (a <= l && r <= b) {
      return vec[k];
    }
    if (r <= a || b <= l) {
      return 0;
    }

    int v1 = sum(a, b, k * 2, l, (l + r) / 2),
        v2 = sum(a, b, k * 2 + 1, (l + r) / 2, r);
    return v1 + v2;
  }
};

int tentou(vector<int> ve) {
  segsum ss;
  ss.shoki1();
  ss.shoki2();
  int ans = 0;
  for (auto v : ve) {
    ans += ss.sum(v + 1, ss.cor);
    ss.updadd(v, 1);
  }
  return ans;
}

vector<int> G[26];

signed main() {

  cin.tie(0);
  ios::sync_with_stdio(false);

  string s;
  cin >> s;
  int l = s.length();
  int n = l;
  for (int i = 0; i < l; i++) {
    G[s[i] - 'a'].pb(i);
  }
  int ki = 0;
  for (int i = 0; i < 26; i++)
    if (G[i].size() % 2)
      ki++;
  if (ki > 1) {
    cout << -1 << endl;
    return 0;
  }
  vector<int> mae, ato;
  int ma;
  vector<int> hai(n);
  int p1 = 1, p2 = -1;
  for (int i = 0; i < 26; i++) {
    int y = G[i].size();
    for (int j = 0; j < y / 2; j++) {
      mae.pb(G[i][j]);
      hai[G[i][j]] = p1;
      p1++;
    }
    for (int j = y - 1; j >= y - y / 2; j--) {
      ato.pb(G[i][j]);
      hai[G[i][j]] = p2;
      p2--;
    }
    if (y % 2)
      ma = G[i][y / 2], hai[G[i][y / 2]] = 0;
  }
  sort(mae.begin(), mae.end());
  sort(ato.begin(), ato.end());
  vector<int> Z(n);
  for (int i = 0; i < n / 2; i++)
    Z[mae[i]] = i;
  if (n % 2)
    Z[ma] = n / 2;
  for (int i = 0; i < n / 2; i++)
    Z[ato[i]] = n / 2 + n % 2 + i;

  int ans = tentou(Z);

  mae.clear(), ato.clear();
  for (int i = 0; i < n; i++)
    if (hai[i] > 0)
      mae.pb(hai[i]);
  for (int i = n - 1; i >= 0; i--)
    if (hai[i] < 0)
      ato.pb(-hai[i]);

  vector<int> henkou(n / 2);
  for (int i = 0; i < n / 2; i++)
    henkou[mae[i]] = i + 1;
  for (int i = 0; i < n / 2; i++)
    ato[i] = henkou[ato[i]] - 1;
  ans += tentou(ato);

  cout << ans << endl;

  return 0;
}


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

//    #include <boost/multiprecision/cpp_int.hpp>
#define int long long
#define inf 1000000007
#define pa pair<int, int>
#define ll long long
#define pal pair<double, double>
#define ppap pair<pa, int>
#define PI 3.14159265358979323846
#define paa pair<int, char>
#define mp make_pair
#define pb push_back
#define EPS (1e-8)

int dx[8] = {0, 1, 0, -1, 1, 1, -1, -1};
int dy[8] = {1, 0, -1, 0, -1, 1, 1, -1};
using namespace std;
class pa3 {
public:
  int x;
  int y, z;
  pa3(int x = 0, int y = 0, int z = 0) : x(x), y(y), z(z) {}
  bool operator<(const pa3 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    return z < p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa3 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    return z > p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa3 &p) const {
    return x == p.x && y == p.y && z == p.z;
  }
  bool operator!=(const pa3 &p) const {
    return !(x == p.x && y == p.y && z == p.z);
  }
};

class pa4 {
public:
  int x;
  int y, z, w;
  pa4(int x = 0, int y = 0, int z = 0, int w = 0) : x(x), y(y), z(z), w(w) {}
  bool operator<(const pa4 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    if (z != p.z)
      return z < p.z;
    return w < p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa4 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    if (z != p.z)
      return z > p.z;
    return w > p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa4 &p) const {
    return x == p.x && y == p.y && z == p.z && w == p.w;
  }
};
class pa2 {
public:
  int x, y;
  pa2(int x = 0, int y = 0) : x(x), y(y) {}
  pa2 operator+(pa2 p) { return pa2(x + p.x, y + p.y); }
  pa2 operator-(pa2 p) { return pa2(x - p.x, y - p.y); }
  bool operator<(const pa2 &p) const { return y != p.y ? y < p.y : x < p.x; }
  bool operator>(const pa2 &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const pa2 &p) const {
    return abs(x - p.x) == 0 && abs(y - p.y) == 0;
  }
  bool operator!=(const pa2 &p) const {
    return !(abs(x - p.x) == 0 && abs(y - p.y) == 0);
  }
};

string itos(int i) {
  ostringstream s;
  s << i;
  return s.str();
}

int gcd(int v, int b) {
  if (v == 0)
    return b;
  if (b == 0)
    return v;
  if (v > b)
    return gcd(b, v);
  if (v == b)
    return b;
  if (b % v == 0)
    return v;
  return gcd(v, b % v);
}

int mod;
int extgcd(int a, int b, int &x, int &y) {
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  }
  int d = extgcd(b, a % b, y, x);
  y -= a / b * x;
  return d;
}
pa operator+(const pa &l, const pa &r) {
  return {l.first + r.first, l.second + r.second};
}
pa operator-(const pa &l, const pa &r) {
  return {l.first - r.first, l.second - r.second};
}

int pr[1000010];
int inv[1000010];

int beki(int wa, int rr, int warukazu) {
  if (rr == 0)
    return 1 % warukazu;
  if (rr == 1)
    return wa % warukazu;
  wa %= warukazu;
  if (rr % 2 == 1)
    return ((ll)beki(wa, rr - 1, warukazu) * (ll)wa) % warukazu;
  ll zx = beki(wa, rr / 2, warukazu);
  return (zx * zx) % warukazu;
}

int comb(int nn, int rr) {
  if (rr < 0 || rr > nn || nn < 0)
    return 0;
  int r = pr[nn] * inv[rr];
  r %= mod;
  r *= inv[nn - rr];
  r %= mod;
  return r;
}

void gya(int ert) {
  pr[0] = 1;
  for (int i = 1; i <= ert; i++) {
    pr[i] = (pr[i - 1] * i) % mod;
  }
  inv[ert] = beki(pr[ert], mod - 2, mod);
  for (int i = ert - 1; i >= 0; i--) {
    inv[i] = inv[i + 1] * (i + 1) % mod;
  }
}

//   cin.tie(0);
//	ios::sync_with_stdio(false);
// priority_queue<pa3,vector<pa3>,greater<pa3>> pq;
// sort(ve.begin(),ve.end(),greater<int>());
//   mt19937(clock_per_sec);
//  mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()) ;

//----------------kokomade tenpure------------

struct segsum {
  //       1
  //   2        3
  // 4   5   6    7

private:
public:
  // (1<<15)=32768
  // 1<<16 = 65536
  // 1<<17 = 131072
  // 1<<18 = 262144

  int cor = (1 << 18);

  vector<int> vec;
  vector<int> lazy;

  void shoki1() { vec.resize(2 * cor + 3, 0); }
  void shoki2() {
    for (int i = cor - 1; i > 0; i--)
      vec[i] = vec[2 * i] + vec[2 * i + 1];
  }
  void clear() {

    for (int i = 0; i < (int)vec.size(); i++)
      vec[i] = 0;
  }
  void updadd(int x, int w) {
    // x 項目に w加算
    x += cor;
    vec[x] += w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }

  void updchan(int x, int w) {
    // x項目をwに変更
    x += cor;
    vec[x] = w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }
  // [a,b)
  // k-th node
  // k no kukanha [l,r)
  int sum(int a, int b, int k = 1, int l = 0, int r = -10) {
    if (r < 0)
      r = cor;

    //	cout<<a<<" "<<b<<" "<<k<<" "<<l<<" "<<r<<endl;

    if (a <= l && r <= b) {
      return vec[k];
    }
    if (r <= a || b <= l) {
      return 0;
    }

    int v1 = sum(a, b, k * 2, l, (l + r) / 2),
        v2 = sum(a, b, k * 2 + 1, (l + r) / 2, r);
    return v1 + v2;
  }
};

int tentou(vector<int> ve) {
  segsum ss;
  ss.shoki1();
  ss.shoki2();
  int ans = 0;
  for (auto v : ve) {
    ans += ss.sum(v + 1, ss.cor);
    ss.updadd(v, 1);
  }
  return ans;
}

vector<int> G[26];

signed main() {

  cin.tie(0);
  ios::sync_with_stdio(false);

  string s;
  cin >> s;
  int l = s.length();
  int n = l;
  for (int i = 0; i < l; i++) {
    G[s[i] - 'a'].pb(i);
  }
  int ki = 0;
  for (int i = 0; i < 26; i++)
    if (G[i].size() % 2)
      ki++;
  if (ki > 1) {
    cout << -1 << endl;
    return 0;
  }
  vector<int> mae, ato;
  int ma;
  vector<int> hai(n);
  int p1 = 1, p2 = -1;
  for (int i = 0; i < 26; i++) {
    int y = G[i].size();
    for (int j = 0; j < y / 2; j++) {
      mae.pb(G[i][j]);
      hai[G[i][j]] = p1;
      p1++;
    }
    for (int j = y - 1; j >= y - y / 2; j--) {
      ato.pb(G[i][j]);
      hai[G[i][j]] = p2;
      p2--;
    }
    if (y % 2)
      ma = G[i][y / 2], hai[G[i][y / 2]] = 0;
  }
  sort(mae.begin(), mae.end());
  sort(ato.begin(), ato.end());
  vector<int> Z(n);
  for (int i = 0; i < n / 2; i++)
    Z[mae[i]] = i;
  if (n % 2)
    Z[ma] = n / 2;
  for (int i = 0; i < n / 2; i++)
    Z[ato[i]] = n / 2 + n % 2 + i;

  int ans = tentou(Z);

  mae.clear(), ato.clear();
  for (int i = 0; i < n; i++)
    if (hai[i] > 0)
      mae.pb(hai[i]);
  for (int i = n - 1; i >= 0; i--)
    if (hai[i] < 0)
      ato.pb(-hai[i]);

  vector<int> henkou(n / 2 + 5);
  for (int i = 0; i < n / 2; i++)
    henkou[mae[i]] = i + 1;
  for (int i = 0; i < n / 2; i++)
    ato[i] = henkou[ato[i]] - 1;
  ans += tentou(ato);

  cout << ans << endl;

  return 0;
}