Problem p02691 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <cmath>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <stdio.h>
#include <vector>
using namespace std;
#define int long long
#define double long double
#define rep(s, i, n) for (int i = s; i < n; i++)
#define c(n) cout << n << endl;
#define ic(n)                                                                  \\
  int n;                                                                       \\
  cin >> n;
#define sc(s)                                                                  \\
  string s;                                                                    \\
  cin >> s;
#define mod 1000000007
#define inf 1000000000000000007
#define f first
#define s second
#define mini(c, a, b) *min_element(c + a, c + b)
#define maxi(c, a, b) *max_element(c + a, c + b)
#define pi 3.141592653589793238462643383279
#define e_ 2.718281828459045235360287471352
#define P pair<int, int>
// printf("%.12Lf\\n",);
int keta(int x) {
  rep(0, i, 30) {
    if (x < 10) {
      return i + 1;
    }
    x = x / 10;
  }
}
int gcd(int x, int y) {
  int aa = x, bb = y;
  rep(0, i, 1000) {
    aa = aa % bb;
    if (aa == 0) {
      return bb;
    }
    bb = bb % aa;
    if (bb == 0) {
      return aa;
    }
  }
}
int lcm(int x, int y) {
  int aa = x, bb = y;
  rep(0, i, 1000) {
    aa = aa % bb;
    if (aa == 0) {
      return x / bb * y;
    }
    bb = bb % aa;
    if (bb == 0) {
      return x / aa * y;
    }
  }
}
bool p(int x) {
  if (x == 1)
    return false;
  rep(2, i, sqrt(x) + 1) {
    if (x % i == 0 && x != i) {
      return false;
    }
  }
  return true;
}
int max(int a, int b) {
  if (a >= b)
    return a;
  else
    return b;
}
string maxst(string s, string t) {
  int n = s.size();
  int m = t.size();
  if (n > m)
    return s;
  else if (n < m)
    return t;
  else {
    rep(0, i, n) {
      if (s[i] > t[i])
        return s;
      if (s[i] < t[i])
        return t;
    }
    return s;
  }
}
int min(int a, int b) {
  if (a >= b)
    return b;
  else
    return a;
}
int n2[41];
int nis[41];
int nia[41];
int mody[41];
int nn;
int com(int n, int y) {
  int ni = 1;
  for (int i = 0; i < 41; i++) {
    n2[i] = ni;
    ni *= 2;
  }
  int bunsi = 1, bunbo = 1;
  rep(0, i, y) bunsi = (bunsi * (n - i)) % mod;
  rep(0, i, y) bunbo = (bunbo * (i + 1)) % mod;
  mody[0] = bunbo;
  rep(1, i, 41) {
    bunbo = (bunbo * bunbo) % mod;
    mody[i] = bunbo;
  }
  rep(0, i, 41) nis[i] = 0;
  nn = mod - 2;
  for (int i = 40; i >= 0; i -= 1) {
    if (nn > n2[i]) {
      nis[i]++;
      nn -= n2[i];
    }
  }
  nis[0]++;
  rep(0, i, 41) {
    if (nis[i] == 1) {
      bunsi = (bunsi * mody[i]) % mod;
    }
  }
  return bunsi;
}
int gyakugen(int n, int y) {
  int ni = 1;
  for (int i = 0; i < 41; i++) {
    n2[i] = ni;
    ni *= 2;
  }
  mody[0] = y;
  rep(1, i, 41) {
    y = (y * y) % mod;
    mody[i] = y;
  }
  rep(0, i, 41) nis[i] = 0;
  nn = mod - 2;
  for (int i = 40; i >= 0; i -= 1) {
    if (nn > n2[i]) {
      nis[i]++;
      nn -= n2[i];
    }
  }
  nis[0]++;
  rep(0, i, 41) {
    if (nis[i] == 1) {
      n = (n * mody[i]) % mod;
    }
  }
  return n;
}
int yakuwa(int n) {
  int sum = 0;
  rep(1, i, sqrt(n + 1)) {
    if (n % i == 0)
      sum += i + n / i;
    if (i * i == n)
      sum -= i;
  }
  return sum;
}
bool integer(double n) {
  if (n == long(n))
    return true;
  else
    return false;
}
int poow(int y, int n) {
  if (n == 0)
    return 1;
  n -= 1;
  int ni = 1;
  for (int i = 0; i < 41; i++) {
    n2[i] = ni;
    ni *= 2;
  }
  int yy = y;
  mody[0] = yy;
  rep(1, i, 41) {
    yy = (yy * yy) % mod;
    mody[i] = yy;
  }
  rep(0, i, 41) nis[i] = 0;
  nn = n;
  for (int i = 40; i >= 0; i -= 1) {
    if (nn >= n2[i]) {
      nis[i]++;
      nn -= n2[i];
    }
  }
  rep(0, i, 41) {
    if (nis[i] == 1) {
      y = (y * mody[i]) % mod;
    }
  }
  return y;
}
int minpow(int x, int y) {
  int sum = 1;
  rep(0, i, y) sum *= x;
  return sum;
}
int ketawa(int x, int sinsuu) {
  int sum = 0;
  rep(0, i, 100) sum += (x % poow(sinsuu, i + 1)) / (poow(sinsuu, i));
  return sum;
}
int sankaku(int a) { return a * (a + 1) / 2; }
bool search(int x) {
  int n;
  int a[n];
  int l = 0, r = n;
  while (r - l >= 1) {
    int i = (l + r) / 2;
    if (a[i] == x)
      return true;
    else if (a[i] < x)
      l = i + 1;
    else
      r = i;
  }
  return false;
}
/*using Graph=vector<vector<int>>;
int oya[114514];
int depth[114514];
void dfs(const Graph &G, int v, int p, int d) {
    depth[v] = d;
    oya[v]=p;
    for (auto nv : G[v]) {
       if (nv == p) continue; // nv が親 p だったらダメ
       dfs(G, nv, v, d+1); // d を 1 増やして子ノードへ
    }
}*/
/*int H=10,W=10;
char field[10][10];
char memo[10][10];
void dfs(int h, int w) {
    memo[h][w] = 'x';

    // 八方向を探索
    for (int dh = -1; dh <= 1; ++dh) {
        for (int dw = -1; dw <= 1; ++dw) {
                if(abs(0-dh)+abs(0-dw)==2)continue;
            int nh = h + dh, nw = w + dw;

            // 場外アウトしたり、0 だったりはスルー
            if (nh < 0 || nh >= H || nw < 0 || nw >= W) continue;
            if (memo[nh][nw] == 'x') continue;

            // 再帰的に探索
            dfs(nh, nw);
        }
    }
}*/
int XOR(int a, int b) {
  int ni = 1;
  rep(0, i, 41) {
    n2[i] = ni;
    ni *= 2;
  }
  rep(0, i, 41) nis[i] = 0;
  for (int i = 40; i >= 0; i -= 1) {
    if (a >= n2[i]) {
      nis[i]++;
      a -= n2[i];
    }
    if (b >= n2[i]) {
      nis[i]++;
      b -= n2[i];
    }
  }
  int sum = 0;
  rep(0, i, 41) sum += (nis[i] % 2 * n2[i]);
  return sum;
}
// int ma[1024577][21];
// for(int bit=0;bit<(1<<n);bit++)rep(0,i,n)if(bit&(1<<i))ma[bit][i]=1;
int a[214514];
int b[214514], c[214514];
signed main() {
  ic(n) rep(0, i, n) cin >> a[i];
  rep(0, i, n) b[i] = a[i] - i;
  rep(0, i, n) c[i] = -(a[i] + i);
  sort(c, c + n);
  int ans = 0;
  rep(0, i, n) {
    ans +=
        (upper_bound(c, c + n, b[i]) - c) - (lower_bound(c, c + n, b[i]) - c);
  }
  c(ans)
}


Error: TLE

Fixed submission:

#include <algorithm>
#include <cmath>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <stdio.h>
#include <vector>
using namespace std;
#define int long long
#define double long double
#define rep(s, i, n) for (int i = s; i < n; i++)
#define c(n) cout << n << endl;
#define ic(n)                                                                  \\
  int n;                                                                       \\
  cin >> n;
#define sc(s)                                                                  \\
  string s;                                                                    \\
  cin >> s;
#define mod 1000000007
#define inf 1000000000000000007
#define f first
#define s second
#define mini(c, a, b) *min_element(c + a, c + b)
#define maxi(c, a, b) *max_element(c + a, c + b)
#define pi 3.141592653589793238462643383279
#define e_ 2.718281828459045235360287471352
#define P pair<int, int>
// printf("%.12Lf\\n",);
int keta(int x) {
  rep(0, i, 30) {
    if (x < 10) {
      return i + 1;
    }
    x = x / 10;
  }
}
int gcd(int x, int y) {
  int aa = x, bb = y;
  rep(0, i, 1000) {
    aa = aa % bb;
    if (aa == 0) {
      return bb;
    }
    bb = bb % aa;
    if (bb == 0) {
      return aa;
    }
  }
}
int lcm(int x, int y) {
  int aa = x, bb = y;
  rep(0, i, 1000) {
    aa = aa % bb;
    if (aa == 0) {
      return x / bb * y;
    }
    bb = bb % aa;
    if (bb == 0) {
      return x / aa * y;
    }
  }
}
bool p(int x) {
  if (x == 1)
    return false;
  rep(2, i, sqrt(x) + 1) {
    if (x % i == 0 && x != i) {
      return false;
    }
  }
  return true;
}
int max(int a, int b) {
  if (a >= b)
    return a;
  else
    return b;
}
string maxst(string s, string t) {
  int n = s.size();
  int m = t.size();
  if (n > m)
    return s;
  else if (n < m)
    return t;
  else {
    rep(0, i, n) {
      if (s[i] > t[i])
        return s;
      if (s[i] < t[i])
        return t;
    }
    return s;
  }
}
int min(int a, int b) {
  if (a >= b)
    return b;
  else
    return a;
}
int n2[41];
int nis[41];
int nia[41];
int mody[41];
int nn;
int com(int n, int y) {
  int ni = 1;
  for (int i = 0; i < 41; i++) {
    n2[i] = ni;
    ni *= 2;
  }
  int bunsi = 1, bunbo = 1;
  rep(0, i, y) bunsi = (bunsi * (n - i)) % mod;
  rep(0, i, y) bunbo = (bunbo * (i + 1)) % mod;
  mody[0] = bunbo;
  rep(1, i, 41) {
    bunbo = (bunbo * bunbo) % mod;
    mody[i] = bunbo;
  }
  rep(0, i, 41) nis[i] = 0;
  nn = mod - 2;
  for (int i = 40; i >= 0; i -= 1) {
    if (nn > n2[i]) {
      nis[i]++;
      nn -= n2[i];
    }
  }
  nis[0]++;
  rep(0, i, 41) {
    if (nis[i] == 1) {
      bunsi = (bunsi * mody[i]) % mod;
    }
  }
  return bunsi;
}
int gyakugen(int n, int y) {
  int ni = 1;
  for (int i = 0; i < 41; i++) {
    n2[i] = ni;
    ni *= 2;
  }
  mody[0] = y;
  rep(1, i, 41) {
    y = (y * y) % mod;
    mody[i] = y;
  }
  rep(0, i, 41) nis[i] = 0;
  nn = mod - 2;
  for (int i = 40; i >= 0; i -= 1) {
    if (nn > n2[i]) {
      nis[i]++;
      nn -= n2[i];
    }
  }
  nis[0]++;
  rep(0, i, 41) {
    if (nis[i] == 1) {
      n = (n * mody[i]) % mod;
    }
  }
  return n;
}
int yakuwa(int n) {
  int sum = 0;
  rep(1, i, sqrt(n + 1)) {
    if (n % i == 0)
      sum += i + n / i;
    if (i * i == n)
      sum -= i;
  }
  return sum;
}
bool integer(double n) {
  if (n == long(n))
    return true;
  else
    return false;
}
int poow(int y, int n) {
  if (n == 0)
    return 1;
  n -= 1;
  int ni = 1;
  for (int i = 0; i < 41; i++) {
    n2[i] = ni;
    ni *= 2;
  }
  int yy = y;
  mody[0] = yy;
  rep(1, i, 41) {
    yy = (yy * yy) % mod;
    mody[i] = yy;
  }
  rep(0, i, 41) nis[i] = 0;
  nn = n;
  for (int i = 40; i >= 0; i -= 1) {
    if (nn >= n2[i]) {
      nis[i]++;
      nn -= n2[i];
    }
  }
  rep(0, i, 41) {
    if (nis[i] == 1) {
      y = (y * mody[i]) % mod;
    }
  }
  return y;
}
int minpow(int x, int y) {
  int sum = 1;
  rep(0, i, y) sum *= x;
  return sum;
}
int ketawa(int x, int sinsuu) {
  int sum = 0;
  rep(0, i, 100) sum += (x % poow(sinsuu, i + 1)) / (poow(sinsuu, i));
  return sum;
}
int sankaku(int a) { return a * (a + 1) / 2; }
bool search(int x) {
  int n;
  int a[n];
  int l = 0, r = n;
  while (r - l >= 1) {
    int i = (l + r) / 2;
    if (a[i] == x)
      return true;
    else if (a[i] < x)
      l = i + 1;
    else
      r = i;
  }
  return false;
}
/*using Graph=vector<vector<int>>;
int oya[114514];
int depth[114514];
void dfs(const Graph &G, int v, int p, int d) {
    depth[v] = d;
    oya[v]=p;
    for (auto nv : G[v]) {
       if (nv == p) continue; // nv が親 p だったらダメ
       dfs(G, nv, v, d+1); // d を 1 増やして子ノードへ
    }
}*/
/*int H=10,W=10;
char field[10][10];
char memo[10][10];
void dfs(int h, int w) {
    memo[h][w] = 'x';

    // 八方向を探索
    for (int dh = -1; dh <= 1; ++dh) {
        for (int dw = -1; dw <= 1; ++dw) {
                if(abs(0-dh)+abs(0-dw)==2)continue;
            int nh = h + dh, nw = w + dw;

            // 場外アウトしたり、0 だったりはスルー
            if (nh < 0 || nh >= H || nw < 0 || nw >= W) continue;
            if (memo[nh][nw] == 'x') continue;

            // 再帰的に探索
            dfs(nh, nw);
        }
    }
}*/
int XOR(int a, int b) {
  int ni = 1;
  rep(0, i, 41) {
    n2[i] = ni;
    ni *= 2;
  }
  rep(0, i, 41) nis[i] = 0;
  for (int i = 40; i >= 0; i -= 1) {
    if (a >= n2[i]) {
      nis[i]++;
      a -= n2[i];
    }
    if (b >= n2[i]) {
      nis[i]++;
      b -= n2[i];
    }
  }
  int sum = 0;
  rep(0, i, 41) sum += (nis[i] % 2 * n2[i]);
  return sum;
}
// int ma[1024577][21];
// for(int bit=0;bit<(1<<n);bit++)rep(0,i,n)if(bit&(1<<i))ma[bit][i]=1;
int a[214514];
signed main() {
  ic(n) rep(0, i, n) cin >> a[i];
  int sum = 0;
  rep(0, i, n) {
    rep(i + 1, j, n) {
      if (a[i] + a[j] == j - i)
        sum++;
    }
  }
  c(sum)
}