Problem p00930 (C++)

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

using namespace std;

struct T;
#define null ((T *)NULL)

typedef int ll;

struct T {
  ll v;
  ll m;
  int c;
  T *l, *r;
  bool lz;
  ll lazy;
  T() {}
  T(ll v) : v(v), m(v), c(1), l(null), r(null), lz(false), lazy(0) {}
};

int hogeS = 0;
#define SSS 2222222
T hoge[SSS];
inline T *New(int v) {
  if (hogeS >= SSS)
    exit(-1);
  hoge[hogeS] = T(v);
  return &hoge[hogeS++];
}
inline int count(T *t) { return t ? t->c : 0; }
inline void push(T *t) {
  if (!t)
    return;
  if (t->lz) {
    t->v += t->lazy;
    t->m += t->lazy;
    t->lz = false;
    if (t->r) {
      t->r->lz |= true;
      t->r->lazy += t->lazy;
    }
    if (t->l) {
      t->l->lz |= true;
      t->l->lazy += t->lazy;
    }
    t->lazy = 0;
  }
}
inline ll mini(T *t) {
  push(t);
  return t ? t->m : LLONG_MAX;
}

inline T *update(T *t) {
  if (!t)
    return t;
  push(t);
  t->c = count(t->l) + count(t->r) + 1;
  t->m = min(t->v, min(mini(t->l), mini(t->r)));
  return t;
}

T *merge(T *a, T *b) {
  push(a);
  push(b);
  if (!a || !b)
    return a ? a : b;
  if (rand() % (count(a) + count(b)) < count(a)) {
    a->r = merge(a->r, b);
    return update(a);
  } else {
    b->l = merge(a, b->l);
    return update(b);
  }
}

pair<T *, T *> split(T *a, int k) {
  push(a);
  if (!a)
    return make_pair(null, null);
  if (k <= count(a->l)) {
    pair<T *, T *> s = split(a->l, k);
    a->l = s.second;
    return make_pair(s.first, update(a));
  } else {
    pair<T *, T *> s = split(a->r, k - count(a->l) - 1);
    a->r = s.first;
    return make_pair(update(a), s.second);
  }
}

inline T *insert(T *t, int k, int v) {
  push(t);
  pair<T *, T *> a = split(t, k);
  return merge(merge(a.first, New(v)), a.second);
}

inline T *add(T *t, int l, int r, int k) {
  push(t);
  pair<T *, T *> u = split(t, r);
  pair<T *, T *> v = split(u.first, l);
  T *w = v.second;
  w->lz = true;
  w->lazy += k;
  return merge(merge(v.first, update(w)), u.second);
}

int n, m;
char s[333333];

void print(T *t) {
  if (t == null)
    return;
  push(t);
  print(t->l);
  printf("%2lld,%2lld|", t->v, t->m);
  print(t->r);
}

int main(void) {
  T *root = null;
  int n, q;
  set<int> toji;
  scanf("%d%d", &n, &q);
  scanf("%s", s);
  for (int i = 0; i < n; i++) {
    root = insert(root, i, 0);
  }
  for (int i = 0; i < n; i++) {
    root = add(root, i, n, s[i] == '(' ? 1 : -1);
    if (s[i] == ')')
      toji.insert(i);
  }
  int k;
  for (int ii = 0; ii < q; ii++) {
    scanf("%d", &k);
    if (s[k - 1] == '(') {
      s[k - 1] = ')';
      toji.insert(k - 1);
      root = add(root, k - 1, n, -2);
      int me = *(toji.begin());
      printf("%d\n", me + 1);
      s[me] = '(';
      toji.erase(me);
      root = add(root, me, n, 2);
    } else {
      toji.erase(k - 1);
      s[k - 1] = '(';
      root = add(root, k - 1, n, 2);
      int l = 0, r = n;
      while (l < r) {
        int mb = (l + r) / 2;
        auto t = split(root, mb);
        if (mini(t.second) >= 2) {
          r = mb;
        } else {
          l = mb + 1;
        }
        root = merge(t.first, t.second);
      }
      printf("%d\n", l + 1);
      s[l] = ')';
      toji.insert(l);
      root = add(root, l, n, -2);
    }
  }
  return 0;
}

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

using namespace std;

struct T;
#define null ((T *)NULL)

typedef int ll;

struct T {
  ll v;
  ll m;
  int c;
  T *l, *r;
  bool lz;
  ll lazy;
  T() {}
  T(ll v) : v(v), m(v), c(1), l(null), r(null), lz(false), lazy(0) {}
};

int hogeS = 0;
#define SSS 2222222
T hoge[SSS];
inline T *New(int v) {
  if (hogeS >= SSS)
    exit(-1);
  hoge[hogeS] = T(v);
  return &hoge[hogeS++];
}
inline int count(T *t) { return t ? t->c : 0; }
inline void push(T *t) {
  if (!t)
    return;
  if (t->lz) {
    t->v += t->lazy;
    t->m += t->lazy;
    t->lz = false;
    if (t->r) {
      t->r->lz |= true;
      t->r->lazy += t->lazy;
    }
    if (t->l) {
      t->l->lz |= true;
      t->l->lazy += t->lazy;
    }
    t->lazy = 0;
  }
}
inline ll mini(T *t) {
  push(t);
  return t ? t->m : INT_MAX;
}

inline T *update(T *t) {
  if (!t)
    return t;
  push(t);
  t->c = count(t->l) + count(t->r) + 1;
  t->m = min(t->v, min(mini(t->l), mini(t->r)));
  return t;
}

T *merge(T *a, T *b) {
  push(a);
  push(b);
  if (!a || !b)
    return a ? a : b;
  if (rand() % (count(a) + count(b)) < count(a)) {
    a->r = merge(a->r, b);
    return update(a);
  } else {
    b->l = merge(a, b->l);
    return update(b);
  }
}

pair<T *, T *> split(T *a, int k) {
  push(a);
  if (!a)
    return make_pair(null, null);
  if (k <= count(a->l)) {
    pair<T *, T *> s = split(a->l, k);
    a->l = s.second;
    return make_pair(s.first, update(a));
  } else {
    pair<T *, T *> s = split(a->r, k - count(a->l) - 1);
    a->r = s.first;
    return make_pair(update(a), s.second);
  }
}

inline T *insert(T *t, int k, int v) {
  push(t);
  pair<T *, T *> a = split(t, k);
  return merge(merge(a.first, New(v)), a.second);
}

inline T *add(T *t, int l, int r, int k) {
  push(t);
  pair<T *, T *> u = split(t, r);
  pair<T *, T *> v = split(u.first, l);
  T *w = v.second;
  w->lz = true;
  w->lazy += k;
  return merge(merge(v.first, update(w)), u.second);
}

int n, m;
char s[333333];

void print(T *t) {
  if (t == null)
    return;
  push(t);
  print(t->l);
  printf("%2lld,%2lld|", t->v, t->m);
  print(t->r);
}

int main(void) {
  T *root = null;
  int n, q;
  set<int> toji;
  scanf("%d%d", &n, &q);
  scanf("%s", s);
  for (int i = 0; i < n; i++) {
    root = insert(root, i, 0);
  }
  for (int i = 0; i < n; i++) {
    root = add(root, i, n, s[i] == '(' ? 1 : -1);
    if (s[i] == ')')
      toji.insert(i);
  }
  int k;
  for (int ii = 0; ii < q; ii++) {
    scanf("%d", &k);
    if (s[k - 1] == '(') {
      s[k - 1] = ')';
      toji.insert(k - 1);
      root = add(root, k - 1, n, -2);
      int me = *(toji.begin());
      printf("%d\n", me + 1);
      s[me] = '(';
      toji.erase(me);
      root = add(root, me, n, 2);
    } else {
      toji.erase(k - 1);
      s[k - 1] = '(';
      root = add(root, k - 1, n, 2);
      int l = 0, r = n;
      while (l < r) {
        int mb = (l + r) / 2;
        auto t = split(root, mb);
        if (mini(t.second) >= 2) {
          r = mb;
        } else {
          l = mb + 1;
        }
        root = merge(t.first, t.second);
      }
      printf("%d\n", l + 1);
      s[l] = ')';
      toji.insert(l);
      root = add(root, l, n, -2);
    }
  }
  return 0;
}