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

#include <bits/stdc++.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<P, ll> T;

long long int INF = 2e18;
const ll fact_table = 1200008;
double Pi = 3.1415926535897932384626;

priority_queue<ll> pql;
priority_queue<P> pqp;
priority_queue<P> bag;
// big priority queue
priority_queue<ll, vector<ll>, greater<ll>> pqls;
priority_queue<P, vector<P>, greater<P>> pqps;
// small priority queue
// top pop

ll dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
ll dy[8] = {0, 1, 0, -1, 1, -1, -1, 1};
char dir[] = "DRUL";
// ↓,→,↑,←

#define endl "\\n"
#ifdef ENJAPMA
#undef endl
#endif
#define p(x) cout << x << endl;
#define el cout << endl;
#define pe(x) cout << x << " ";
#define ps(x) cout << fixed << setprecision(25) << x << endl;
#define pu(x) cout << (x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define CLEAR(a) a = decltype(a)();
#define pc(x) cout << x << ",";

const ll mod = 998244353ll;
// const ll mod = 1000000007ll;

ll mypow(ll number1, ll number2, ll mod) {
  if (number2 == 0) {
    return 1ll;
  } else {
    ll number3 = mypow(number1, number2 / 2, mod);
    number3 *= number3;
    number3 %= mod;
    if (number2 % 2 == 1) {
      number3 *= number1;
      number3 %= mod;
    }
    return number3;
  }
}
void YES(bool condition) {
  if (condition) {
    p("YES");
  } else {
    p("NO");
  }
  return;
}
void Yes(bool condition) {
  if (condition) {
    p("Yes");
  } else {
    p("No");
  }
  return;
}
/*
ll fact[fact_table + 5],rfact[fact_table + 5];

void c3_init(){
    fact[0] = rfact[0] = 1;
    for(ll i=1; i<=fact_table; i++){
        fact[i] = (fact[i-1]*i) % mod;
    }
    rfact[fact_table] = mypow(fact[fact_table],mod - 2, mod);
    for(ll i=fact_table; i>=1; i--){
       rfact[i-1] = rfact[i] * i;
       rfact[i-1] %= mod;
    }
    return;}
ll c3(ll n,ll r){
    assert(n >= r);
    assert(n >= 0);
    assert(r >= 0);
    return (((fact[n] * rfact[r]) % mod ) * rfact[n-r]) % mod;}
*/
bool multicase = false;

ll n, m, num, a, b, c, d, e, q;

ll x[200005], y[100005], z[100005];
ll k;

vector<ll> G[500005];

void solve() {
  map<ll, ll> mp;
  cin >> n;
  for (ll i = 0; i < n; i++) {
    cin >> x[i];
  }
  mp[x[0] + 1] = 1;
  ll ans = 0;
  for (ll i = 1; i < n; i++) {
    ans += mp[i + 1 - x[i]];
    mp[x[i] + i + 1]++;
  }
  p(ans);
  return;
}

int main() {

  // init();
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll q, testcase = 1;
  if (multicase) {
    cin >> q;
  } else {
    q = 1;
  }
  while (q--) {
    // pu("Case ");pu("#");pu(testcase);pu(": ");
    solve();
    testcase++;
  }
  // solve();
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<P, ll> T;

long long int INF = 2e18;
const ll fact_table = 1200008;
double Pi = 3.1415926535897932384626;

priority_queue<ll> pql;
priority_queue<P> pqp;
priority_queue<P> bag;
// big priority queue
priority_queue<ll, vector<ll>, greater<ll>> pqls;
priority_queue<P, vector<P>, greater<P>> pqps;
// small priority queue
// top pop

ll dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
ll dy[8] = {0, 1, 0, -1, 1, -1, -1, 1};
char dir[] = "DRUL";
// ↓,→,↑,←

#define endl "\\n"
#ifdef ENJAPMA
#undef endl
#endif
#define p(x) cout << x << endl;
#define el cout << endl;
#define pe(x) cout << x << " ";
#define ps(x) cout << fixed << setprecision(25) << x << endl;
#define pu(x) cout << (x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define CLEAR(a) a = decltype(a)();
#define pc(x) cout << x << ",";

const ll mod = 998244353ll;
// const ll mod = 1000000007ll;

ll mypow(ll number1, ll number2, ll mod) {
  if (number2 == 0) {
    return 1ll;
  } else {
    ll number3 = mypow(number1, number2 / 2, mod);
    number3 *= number3;
    number3 %= mod;
    if (number2 % 2 == 1) {
      number3 *= number1;
      number3 %= mod;
    }
    return number3;
  }
}
void YES(bool condition) {
  if (condition) {
    p("YES");
  } else {
    p("NO");
  }
  return;
}
void Yes(bool condition) {
  if (condition) {
    p("Yes");
  } else {
    p("No");
  }
  return;
}
/*
ll fact[fact_table + 5],rfact[fact_table + 5];

void c3_init(){
    fact[0] = rfact[0] = 1;
    for(ll i=1; i<=fact_table; i++){
        fact[i] = (fact[i-1]*i) % mod;
    }
    rfact[fact_table] = mypow(fact[fact_table],mod - 2, mod);
    for(ll i=fact_table; i>=1; i--){
       rfact[i-1] = rfact[i] * i;
       rfact[i-1] %= mod;
    }
    return;}
ll c3(ll n,ll r){
    assert(n >= r);
    assert(n >= 0);
    assert(r >= 0);
    return (((fact[n] * rfact[r]) % mod ) * rfact[n-r]) % mod;}
*/
bool multicase = false;

ll n, m, num, a, b, c, d, e, q;

ll x[200005], y[100005], z[100005];
ll k;

vector<ll> G[500005];

void solve() {
  multiset<ll> mt;
  cin >> n;
  for (ll i = 0; i < n; i++) {
    cin >> x[i];
  }
  mt.insert(x[0] + 1);
  ll ans = 0;
  for (ll i = 1; i < n; i++) {
    ans += mt.count((i + 1) - x[i]);
    mt.insert(x[i] + i + 1);
  }
  p(ans);
  return;
}

int main() {

  // init();
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll q, testcase = 1;
  if (multicase) {
    cin >> q;
  } else {
    q = 1;
  }
  while (q--) {
    // pu("Case ");pu("#");pu(testcase);pu(": ");
    solve();
    testcase++;
  }
  // solve();
  return 0;
}