Problem p03059 (C++)

Buggy submission (status: Time Limit Exceeded):
/*#include <iostream>
#include <algorithm>
#include <array>
#include <cmath>
#include <deque>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
*/

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

#define int long long
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define FOR(i, a, b) for (int(i) = (a); (i) < (b); (i)++)
#define REP(i, n) FOR(i, 0, n)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define SORT(c) sort((c).begin(), (c).end())

typedef long long ll;
const ll INF = 1LL << 60;
const ll mod = 1e9 + 7;
const int MAX_N = 5e5 + 5;
int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
vector<ll> prime;

ll inv[MAX_N], fac[MAX_N];

template <class T = ll> T in() {
  T x;
  cin >> x;
  return (x);
}
inline ll GCD(ll a, ll b) {
  ll c;
  while (b != 0) {
    c = a % b;
    a = b;
    b = c;
  }
  return a;
}
inline ll LCM(ll a, ll b) { return a * b / GCD(a, b); }
inline ll POW(ll a, ll b) {
  ll c = 1;
  while (b > 0) {
    if (b & 1) {
      c = a * c % mod;
    }
    a = a * a % mod;
    b >>= 1LL;
  }
  return c;
}
inline void _nCr() {
  fac[0] = 1;
  for (int i = 1LL; i < MAX_N; i++) {
    fac[i] = fac[i - 1] * i % mod;
  }
  for (int i = 0; i < MAX_N; i++) {
    inv[i] = POW(fac[i], mod - 2);
  }
}
inline ll nCr(ll n, ll r) { return (fac[n] * inv[r] % mod) * inv[n - r] % mod; }
inline void PRI(ll n) {
  bool a[n + 1];
  for (int i = 0; i < n + 1; i++) {
    a[i] = 1;
  }
  for (int i = 2; i < n + 1; i++) {
    if (a[i]) {
      prime.pb(i);
      ll b = i;
      while (b <= n) {
        a[b] = 0;
        b += i;
      }
    }
  }
}

typedef pair<int, pair<int, int>> edge;

class UnionFind {
private:
  vector<int> par;

public:
  UnionFind(int N) { par = vector<int>(N, -1LL); }
  int find(int x);
  ll size(int x);
  void unite(int x, int y);
  bool same(int x, int y);
};

class Kruskal {
private:
  UnionFind *uf;
  vector<edge> e;

public:
  vector<edge> mst;
  Kruskal(int N) { uf = new UnionFind(N); }
  void add(int x, int y, ll z);
  void run();
};

//----UnionFind-------------------------------
int UnionFind::find(int x) {
  if (par[x] < 0)
    return x;
  else
    return par[x] = find(par[x]);
}

ll UnionFind::size(int x) { return -par[find(x)]; }

void UnionFind::unite(int x, int y) {
  x = find(x);
  y = find(y);

  // 大きい方に小さい方をくっ付ける
  if (size(x) < size(y))
    swap(x, y);
  par[x] += par[y];
  par[y] = x;
}

bool UnionFind::same(int x, int y) {
  x = find(x);
  y = find(y);
  return x == y;
}

//----Kruskal-------------------------------
void Kruskal::add(int x, int y, ll z) {
  // x < y
  if (x > y)
    swap(x, y);
  e.push_back({z, {x, y}});
}

void Kruskal::run() {
  sort(e.begin(), e.end());
  e.erase(unique(e.begin(), e.end()), e.end());
  for (auto x : e) {
    if (uf->same(x.second.first, x.second.second)) {
      continue;
    } else {
      mst.push_back(x);
      uf->unite(x.second.first, x.second.second);
    }
  }
}

signed main() {
  int a, b, t;
  int ans = 0;
  for (int i = a; i < t + 1; i += a) {
    ans += b;
  }
  cout << ans << endl;
}

Fixed submission:
/*#include <iostream>
#include <algorithm>
#include <array>
#include <cmath>
#include <deque>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
*/

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

#define int long long
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define FOR(i, a, b) for (int(i) = (a); (i) < (b); (i)++)
#define REP(i, n) FOR(i, 0, n)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define SORT(c) sort((c).begin(), (c).end())

typedef long long ll;
const ll INF = 1LL << 60;
const ll mod = 1e9 + 7;
const int MAX_N = 5e5 + 5;
int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
vector<ll> prime;

ll inv[MAX_N], fac[MAX_N];

template <class T = ll> T in() {
  T x;
  cin >> x;
  return (x);
}
inline ll GCD(ll a, ll b) {
  ll c;
  while (b != 0) {
    c = a % b;
    a = b;
    b = c;
  }
  return a;
}
inline ll LCM(ll a, ll b) { return a * b / GCD(a, b); }
inline ll POW(ll a, ll b) {
  ll c = 1;
  while (b > 0) {
    if (b & 1) {
      c = a * c % mod;
    }
    a = a * a % mod;
    b >>= 1LL;
  }
  return c;
}
inline void _nCr() {
  fac[0] = 1;
  for (int i = 1LL; i < MAX_N; i++) {
    fac[i] = fac[i - 1] * i % mod;
  }
  for (int i = 0; i < MAX_N; i++) {
    inv[i] = POW(fac[i], mod - 2);
  }
}
inline ll nCr(ll n, ll r) { return (fac[n] * inv[r] % mod) * inv[n - r] % mod; }
inline void PRI(ll n) {
  bool a[n + 1];
  for (int i = 0; i < n + 1; i++) {
    a[i] = 1;
  }
  for (int i = 2; i < n + 1; i++) {
    if (a[i]) {
      prime.pb(i);
      ll b = i;
      while (b <= n) {
        a[b] = 0;
        b += i;
      }
    }
  }
}

typedef pair<int, pair<int, int>> edge;

class UnionFind {
private:
  vector<int> par;

public:
  UnionFind(int N) { par = vector<int>(N, -1LL); }
  int find(int x);
  ll size(int x);
  void unite(int x, int y);
  bool same(int x, int y);
};

class Kruskal {
private:
  UnionFind *uf;
  vector<edge> e;

public:
  vector<edge> mst;
  Kruskal(int N) { uf = new UnionFind(N); }
  void add(int x, int y, ll z);
  void run();
};

//----UnionFind-------------------------------
int UnionFind::find(int x) {
  if (par[x] < 0)
    return x;
  else
    return par[x] = find(par[x]);
}

ll UnionFind::size(int x) { return -par[find(x)]; }

void UnionFind::unite(int x, int y) {
  x = find(x);
  y = find(y);

  // 大きい方に小さい方をくっ付ける
  if (size(x) < size(y))
    swap(x, y);
  par[x] += par[y];
  par[y] = x;
}

bool UnionFind::same(int x, int y) {
  x = find(x);
  y = find(y);
  return x == y;
}

//----Kruskal-------------------------------
void Kruskal::add(int x, int y, ll z) {
  // x < y
  if (x > y)
    swap(x, y);
  e.push_back({z, {x, y}});
}

void Kruskal::run() {
  sort(e.begin(), e.end());
  e.erase(unique(e.begin(), e.end()), e.end());
  for (auto x : e) {
    if (uf->same(x.second.first, x.second.second)) {
      continue;
    } else {
      mst.push_back(x);
      uf->unite(x.second.first, x.second.second);
    }
  }
}

signed main() {
  int a, b, t;
  cin >> a >> b >> t;
  int ans = 0;
  for (int i = a; i < t + 1; i += a) {
    ans += b;
  }
  cout << ans << endl;
}