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这是第一份代码

#include <bits/stdc++.h>
using namespace std;

template<class T>void Rd(T &x) {
  char c; bool f(1);
  while (!isdigit(c = getchar())) f = c != '-';
  x = T(c ^ 48);
  while (isdigit(c = getchar())) x = x * 10 + (c ^ 48);
  x = f ? x : -x;
}
template<class A, class... B>void Rd(A &x, B& ...y) {
  Rd(x), Rd(y...);
}
template<class T> inline void Cmx(T &a, T b) {
  if (a < b) a = b;
}
template<class T> inline void Cmn(T &a, T b) {
  if (a > b) a = b;
}
#define Wr(...) fprintf(stderr, __VA_ARGS__)

const int N(1e5);
struct Tree {
  int lc, rc; long long sum;
  Tree() {lc = rc = sum = 0;}
};
main() {
  int n, m; Rd(n);
  vector<int> a(n);
  for (int &i : a) Rd(i);
  vector<int> root(n); vector<Tree> tr(1);
  #define mid ((L + R) >> 1)
  function<void(int&, int, int, int, int, int)>
   Build = [&](int &rt, int prt, int L, int R, int p, int x) {
    rt = tr.size(), tr.push_back(tr[prt]), tr[rt].sum += x;
    if (L == R) return ;
    p <= mid ? Build(tr[rt].lc, tr[prt].lc, L, mid, p, x) :
      Build(tr[rt].rc, tr[prt].rc, mid + 1, R, p, x);
  };
  function<long long(int, int, int, int, int, int)>
   Query = [&](int rt, int prt, int L, int R, int l, int r) {
    if (l <= L && R <= r) return tr[rt].sum - tr[prt].sum;
    long long res(0);
    if (l <= mid) res += Query(tr[rt].lc, tr[prt].lc, L, mid, l, r);
    if (r > mid) res += Query(tr[rt].rc, tr[prt].rc, mid + 1, R, l, r);
    return res;
  };
  #undef mid
  for (int i(0); i < n; ++i)
    Build(root[i], i ? root[i - 1] : 0, 1, 1e9, a[i], a[i]);
  Rd(m);
  for (int l, r; m--; ) {
    Rd(l, r), --l, --r;
    int rtl(l ? root[l - 1] : 0), rtr(root[r]);
    for (int ans(1); ; ) {
      int res(Query(rtr, rtl, 1, 1e9, 1, ans));
      if (res >= ans) ans = res + 1;
      else { printf("%d\n", ans); break; }
    }
  }
  return 0;
}

这是第二份代码

#include <bits/stdc++.h>
using namespace std;

template<class T>void Rd(T &x) {
  char c; bool f(1);
  while (!isdigit(c = getchar())) f = c != '-';
  x = T(c ^ 48);
  while (isdigit(c = getchar())) x = x * 10 + (c ^ 48);
  x = f ? x : -x;
}
template<class A, class... B>void Rd(A &x, B& ...y) {
  Rd(x), Rd(y...);
}
template<class T> inline void Cmx(T &a, T b) {
  if (a < b) a = b;
}
template<class T> inline void Cmn(T &a, T b) {
  if (a > b) a = b;
}
#define Wr(...) fprintf(stderr, __VA_ARGS__)

const int N(1e5);
struct Tree {
  int lc, rc, sum;
  Tree() {lc = rc = sum = 0;}
} tr[N * 100 + 5];
int cnt;
#define mid ((L + R) >> 1)
void Build(int &rt, int prt, int L, int R, int p, int x) {
  tr[rt = ++cnt] = tr[prt], tr[rt].sum += x;
  if (L == R) return ;
  p <= mid ? Build(tr[rt].lc, tr[prt].lc, L, mid, p, x) :
    Build(tr[rt].rc, tr[prt].rc, mid + 1, R, p, x);
};
long long Query(int rt, int prt, int L, int R, int l, int r) {
  if (l <= L && R <= r) return tr[rt].sum - tr[prt].sum;
  long long res(0);
  if (l <= mid) res += Query(tr[rt].lc, tr[prt].lc, L, mid, l, r);
  if (r > mid) res += Query(tr[rt].rc, tr[prt].rc, mid + 1, R, l, r);
  return res;
};
#undef mid
main() {
  int n, m; Rd(n);
  vector<int> a(n);
  for (int &i : a) Rd(i);
  vector<int> root(n); vector<Tree> tr(1);
  for (int i(0); i < n; ++i)
    Build(root[i], i ? root[i - 1] : 0, 1, 1e9, a[i], a[i]);
  Rd(m);
  for (int l, r; m--; ) {
    Rd(l, r), --l, --r;
    int rtl(l ? root[l - 1] : 0), rtr(root[r]);
    for (int ans(1); ; ) {
      int res(Query(rtr, rtl, 1, 1e9, 1, ans));
      if (res >= ans) ans = res + 1;
      else { printf("%d\n", ans); break; }
    }
  }
  return 0;
}

表面上看好像基本一直，但是第一份代码怎么会RE捏。

测试信息是：Runtime Error. Received signal 11: Segmentation fault with invalid memory reference.