Problem p02346 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

#define _overload(_1, _2, _3, name, ...) name
#define _rep(i, n) _range(i, 0, n)
#define _range(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rep(...) _overload(__VA_ARGS__, _range, _rep, )(__VA_ARGS__)

#define _rrep(i, n) _rrange(i, n, 0)
#define _rrange(i, a, b) for (int i = (int)(a)-1; i >= (int)(b); --i)
#define rrep(...) _overload(__VA_ARGS__, _rrange, _rrep, )(__VA_ARGS__)

#define _all(arg) begin(arg), end(arg)
#define uniq(arg) sort(_all(arg)), (arg).erase(unique(_all(arg)), end(arg))
#define getidx(ary, key) lower_bound(_all(ary), key) - begin(ary)
#define clr(a, b) memset((a), (b), sizeof(a))
#define bit(n) (1LL << (n))

// #define DEBUG

#ifdef DEBUG
#define dump(...) fprintf(stderr, __VA_ARGS__)
#else
#define dump(...)
#endif

template <class T> bool chmax(T &a, const T &b) {
  return (a < b) ? (a = b, 1) : 0;
}
template <class T> bool chmin(T &a, const T &b) {
  return (b < a) ? (a = b, 1) : 0;
}

using namespace std;
using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

const double EPS = 1e-10;
const double PI = acos(-1.0);
const ll inf = 1LL << 62;
const ll mod = 1000000007LL;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

ll extgcd(ll a, ll b, ll &x, ll &y) {
  x = 1, y = 0;
  ll g = a;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= a / b * x;
  return g;
}
ll ADD(const ll &a, const ll &b, const ll &mod) { return (a + b) % mod; }
ll SUB(const ll &a, const ll &b, const ll &mod) { return (a - b + mod) % mod; }
ll MUL(const ll &a, const ll &b, const ll &mod) { return (1LL * a * b) % mod; }
ll DIV(const ll &a, const ll &b, const ll &mod) {
  ll x, y;
  extgcd(b, mod, x, y);
  return MUL(a, (x + mod) % mod, mod);
}

random_device rd;
mt19937 mt(rd());
uniform_int_distribution<int> dice(1, 6);
uniform_real_distribution<double> score(0.0, 10.0);

struct SegTree {
  int n;
  vi v;

  int pow2fit(int sz) {
    int ret = 1;
    while (ret < sz)
      ret *= 2;
    return ret;
  }

  SegTree(int sz) {
    n = pow2fit(sz);
    v = vi(2 * n - 1);
  }

  // v[a] += x
  int add(int a, int x) {
    int idx = n - 1 + a;
    v[idx] += x;

    while (idx > 0) {
      idx = (idx - 1) / 2;
      v[idx] = v[2 * idx + 1] + v[2 * idx + 2];
    }
  }

  // sum [a, b)
  int getsum(int a, int b, int k = 0, int l = 0, int r = -1) {
    if (r < 0)
      r = n;

    if (a >= r or l >= b)
      return 0;
    if (a <= l and r <= b)
      return v[k];

    return getsum(a, b, 2 * k + 1, l, (l + r) / 2) +
           getsum(a, b, 2 * k + 2, (l + r) / 2, r);
  }
};

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n, Q;
  cin >> n >> Q;
  SegTree seg(n);

  rep(loop, Q) {
    int op, x, y;
    cin >> op >> x >> y;
    if (op == 0) {
      x--;
      seg.add(x, y);
    } else {
      x--;
      cout << seg.getsum(x, y) << endl;
    }
  }

  return 0;
}

Error: 0

Fixed submission:

#include <bits/stdc++.h>

#define _overload(_1, _2, _3, name, ...) name
#define _rep(i, n) _range(i, 0, n)
#define _range(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rep(...) _overload(__VA_ARGS__, _range, _rep, )(__VA_ARGS__)

#define _rrep(i, n) _rrange(i, n, 0)
#define _rrange(i, a, b) for (int i = (int)(a)-1; i >= (int)(b); --i)
#define rrep(...) _overload(__VA_ARGS__, _rrange, _rrep, )(__VA_ARGS__)

#define _all(arg) begin(arg), end(arg)
#define uniq(arg) sort(_all(arg)), (arg).erase(unique(_all(arg)), end(arg))
#define getidx(ary, key) lower_bound(_all(ary), key) - begin(ary)
#define clr(a, b) memset((a), (b), sizeof(a))
#define bit(n) (1LL << (n))

// #define DEBUG

#ifdef DEBUG
#define dump(...) fprintf(stderr, __VA_ARGS__)
#else
#define dump(...)
#endif

template <class T> bool chmax(T &a, const T &b) {
  return (a < b) ? (a = b, 1) : 0;
}
template <class T> bool chmin(T &a, const T &b) {
  return (b < a) ? (a = b, 1) : 0;
}

using namespace std;
using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;

const double EPS = 1e-10;
const double PI = acos(-1.0);
const ll inf = 1LL << 62;
const ll mod = 1000000007LL;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

ll extgcd(ll a, ll b, ll &x, ll &y) {
  x = 1, y = 0;
  ll g = a;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= a / b * x;
  return g;
}
ll ADD(const ll &a, const ll &b, const ll &mod) { return (a + b) % mod; }
ll SUB(const ll &a, const ll &b, const ll &mod) { return (a - b + mod) % mod; }
ll MUL(const ll &a, const ll &b, const ll &mod) { return (1LL * a * b) % mod; }
ll DIV(const ll &a, const ll &b, const ll &mod) {
  ll x, y;
  extgcd(b, mod, x, y);
  return MUL(a, (x + mod) % mod, mod);
}

random_device rd;
mt19937 mt(rd());
uniform_int_distribution<int> dice(1, 6);
uniform_real_distribution<double> score(0.0, 10.0);

struct SegTree {
  int n;
  vi v;

  int pow2fit(int sz) {
    int ret = 1;
    while (ret < sz)
      ret *= 2;
    return ret;
  }

  SegTree(int sz) {
    n = pow2fit(sz);
    v = vi(n);
  }

  // v[a] = x
  int update(int a, int x) {
    int idx = n - 1 + a;
    v[idx] = x;

    while (idx > 0) {
      idx = (idx - 1) / 2;
      v[idx] = v[2 * idx + 1] + v[2 * idx + 2];
    }
  }

  // sum [a, b)
  int getsum(int a, int b, int k = 0, int l = 0, int r = -1) {
    if (r < 0)
      r = n;

    if (a >= r or l >= b)
      return 0;
    if (a <= l and r <= b)
      return v[k];

    return getsum(a, b, 2 * k + 1, l, (l + r) / 2) +
           getsum(a, b, 2 * k + 2, (l + r) / 2, r);
  }
};

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n, Q;
  cin >> n >> Q;
  SegTree seg(n);

  rep(loop, Q) {
    int op, x, y;
    cin >> op >> x >> y;
    if (op == 0) {
      x--;
      seg.update(x, y);
    } else {
      x--;
      cout << seg.getsum(x, y) << endl;
    }
  }

  return 0;
}