Problem p03618 (C++)

Buggy submission (status: Runtime Error):

// MAGRANT - GNC20 - TEMPLATE 3.3
// 2017/8/26 - AtCoder Grand Contest 019 - Beta

// FOR COMPATIBILITY:
#define _CRT_SECURE_NO_WARNINGS

// UNIVERSAL DEFINITIONS:
#define N (1 << 17)
#define MODULO (1000000007)
#define HA1 (2420609)
#define HA2 (19260817)

// FREQUENT HEADER FILES:
#include <algorithm>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

// TEMPLATE BEGINS HERE.
// #define MAGRANT_ALLOWS_CTMP
// IMPORTANT: DO NOT OPEN UNLESS AS CONTESTANT.
// CAUTION: BEWARE OF CONFLICT.
#ifdef MAGRANT_ALLOWS_CTMP
namespace CTMP {
// ELEMENTARY MATHEMATICAL COMPUTATIONS:
long long fact[N], inv[N];
long long KissMe(long long xx, long long yy) {
  if (yy == 0LL) {
    return 1LL;
  }
  long long Res = KissMe((xx * xx) % (long long)MODULO, yy >> 1);
  if (yy % 2LL == 1LL) {
    Res *= xx;
    Res %= (long long)MODULO;
  }
  return Res;
}
inline void InitFactInv() {
  fact[0] = 1LL;
  for (int i = 1; i < N - 4; i++) {
    fact[i] = fact[i - 1] * (long long)i;
    fact[i] %= (long long)MODULO;
  }
  inv[N - 5] = KissMe(fact[N - 5], (long long)(MODULO - 2));
  for (int i = N - 6; i >= 0; i--) {
    inv[i] = inv[i + 1] * (long long)(i + 1);
    inv[i] %= (long long)MODULO;
  }
}
inline long long Choose(int xx, int yy) {
  if (xx < yy) {
    return 0LL;
  } else if (xx == yy) {
    return 1LL;
  }
  long long Res = fact[xx];
  Res *= inv[yy];
  Res %= (long long)MODULO;
  Res *= inv[xx - yy];
  Res %= (long long)MODULO;
  return Res;
}
inline long long GridWays(int fx, int fy, int sx = 0, int sy = 0) {
  fx -= sx, fy -= sy;
  if (fx < 0 || fy < 0) {
    return 0LL;
  }
  long long Res = fact[fx + fy];
  Res *= inv[fx];
  Res %= (long long)MODULO;
  Res *= inv[fy];
  Res %= (long long)MODULO;
  return Res;
}
} // namespace CTMP
#endif
// TEMPLATE FINISHES HERE.

int n;
char s[N];
long long Ans;
int cnt[30];

int main() {
  // IMPORTANT: DO NOT OPEN UNLESS AS CONTESTANT.
  // CAUTION: BEWARE OF CONFLICT.
  // using namespace CTMP;

  // REAFFIRM THE FOLLOWING BEFORE CODING.
  // 1. THE ALGORITHM IS CORRECT.
  // 2. THE COMPLEXITY IS PROPER.
  // 3. THE ALGORITHM CANNOT BE SIMPLER.
  // 4. CODING DETAILS WERE CONSIDERED.

  scanf("%s", s);
  n = strlen(s);
  Ans = 1LL + ((long long)n) * ((long long)(n + 1)) / 2LL;
  for (int i = 0; i < n; i++) {
    cnt[s[i] - 'a']++;
  }
  for (int i = 0; i < 26; i++) {
    Ans -= ((long long)(cnt[i])) * ((long long)(cnt[i] + 1)) / 2LL;
  }
  printf("%lld\n", Ans);

  // REAFFIRM THE FOLLOWING BEFORE SUBMITTING.
  // 1. THE ARRAYS ARE IN PROPER SIZE.
  // 2. THE CORNER CASES WILL NOT LEAD TO VIOLATION.
  // 3. NO TYPO LIKE N->M EXISTS.
  // 4. THE INPUT/OUTPUT IS IN THE SPECIFIED FORMAT.
  // 5. ALL CATEGORIES DO NOT INTERSECT.
  // system("pause");
  return 0;
}


Fixed submission:

// MAGRANT - GNC20 - TEMPLATE 3.3
// 2017/8/26 - AtCoder Grand Contest 019 - Beta

// FOR COMPATIBILITY:
#define _CRT_SECURE_NO_WARNINGS

// UNIVERSAL DEFINITIONS:
#define N (1 << 18)
#define MODULO (1000000007)
#define HA1 (2420609)
#define HA2 (19260817)

// FREQUENT HEADER FILES:
#include <algorithm>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

// TEMPLATE BEGINS HERE.
// #define MAGRANT_ALLOWS_CTMP
// IMPORTANT: DO NOT OPEN UNLESS AS CONTESTANT.
// CAUTION: BEWARE OF CONFLICT.
#ifdef MAGRANT_ALLOWS_CTMP
namespace CTMP {
// ELEMENTARY MATHEMATICAL COMPUTATIONS:
long long fact[N], inv[N];
long long KissMe(long long xx, long long yy) {
  if (yy == 0LL) {
    return 1LL;
  }
  long long Res = KissMe((xx * xx) % (long long)MODULO, yy >> 1);
  if (yy % 2LL == 1LL) {
    Res *= xx;
    Res %= (long long)MODULO;
  }
  return Res;
}
inline void InitFactInv() {
  fact[0] = 1LL;
  for (int i = 1; i < N - 4; i++) {
    fact[i] = fact[i - 1] * (long long)i;
    fact[i] %= (long long)MODULO;
  }
  inv[N - 5] = KissMe(fact[N - 5], (long long)(MODULO - 2));
  for (int i = N - 6; i >= 0; i--) {
    inv[i] = inv[i + 1] * (long long)(i + 1);
    inv[i] %= (long long)MODULO;
  }
}
inline long long Choose(int xx, int yy) {
  if (xx < yy) {
    return 0LL;
  } else if (xx == yy) {
    return 1LL;
  }
  long long Res = fact[xx];
  Res *= inv[yy];
  Res %= (long long)MODULO;
  Res *= inv[xx - yy];
  Res %= (long long)MODULO;
  return Res;
}
inline long long GridWays(int fx, int fy, int sx = 0, int sy = 0) {
  fx -= sx, fy -= sy;
  if (fx < 0 || fy < 0) {
    return 0LL;
  }
  long long Res = fact[fx + fy];
  Res *= inv[fx];
  Res %= (long long)MODULO;
  Res *= inv[fy];
  Res %= (long long)MODULO;
  return Res;
}
} // namespace CTMP
#endif
// TEMPLATE FINISHES HERE.

int n;
char s[N];
long long Ans;
int cnt[30];

int main() {
  // IMPORTANT: DO NOT OPEN UNLESS AS CONTESTANT.
  // CAUTION: BEWARE OF CONFLICT.
  // using namespace CTMP;

  // REAFFIRM THE FOLLOWING BEFORE CODING.
  // 1. THE ALGORITHM IS CORRECT.
  // 2. THE COMPLEXITY IS PROPER.
  // 3. THE ALGORITHM CANNOT BE SIMPLER.
  // 4. CODING DETAILS WERE CONSIDERED.

  scanf("%s", s);
  n = strlen(s);
  Ans = 1LL + ((long long)n) * ((long long)(n + 1)) / 2LL;
  for (int i = 0; i < n; i++) {
    cnt[s[i] - 'a']++;
  }
  for (int i = 0; i < 26; i++) {
    Ans -= ((long long)(cnt[i])) * ((long long)(cnt[i] + 1)) / 2LL;
  }
  printf("%lld\n", Ans);

  // REAFFIRM THE FOLLOWING BEFORE SUBMITTING.
  // 1. THE ARRAYS ARE IN PROPER SIZE.
  // 2. THE CORNER CASES WILL NOT LEAD TO VIOLATION.
  // 3. NO TYPO LIKE N->M EXISTS.
  // 4. THE INPUT/OUTPUT IS IN THE SPECIFIED FORMAT.
  // 5. ALL CATEGORIES DO NOT INTERSECT.
  // system("pause");
  return 0;
}