Problem p02846 (C++)

Buggy submission (status: Runtime Error):
/*
これを入れて実行
g++ code.cpp
./a.out
 */

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <stdio.h>
#include <string>
#include <tuple>
#include <unordered_map>
#include <utility>
#include <vector>

#define all(x) (x).begin(), (x).end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using namespace std;
typedef long long ll;
typedef long double ld;

int dy4[4] = {-1, 0, +1, 0};
int dx4[4] = {0, +1, 0, -1};
int dy8[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
int dx8[8] = {0, 1, 1, 1, 0, -1, -1, -1};

const long long INF = 1LL << 60;
const ll MOD = 1e9 + 7;

bool greaterSecond(const pair<int, int> &f, const pair<int, int> &s) {
  return f.second > s.second;
}

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

ll conbinationMemo[100][100];

void cmemoInit() {
  rep(i, 100) {
    rep(j, 100) { conbinationMemo[i][j] = -1; }
  }
}

ll nCr(ll n, ll r) {
  if (conbinationMemo[n][r] != -1)
    return conbinationMemo[n][r];
  if (r == 0 || r == n) {
    return 1;
  } else if (r == 1) {
    return n;
  }
  return conbinationMemo[n][r] = (nCr(n - 1, r) + nCr(n - 1, r - 1));
}

ll nPr(ll n, ll r) {
  r = n - r;
  ll ret = 1;
  for (ll i = n; i >= r + 1; i--)
    ret *= i;
  return ret;
}
//-----------------------ここから-----------
int main(void) {
  vector<ll> t(2);
  vector<pair<ll, ll>> ab(2);
  rep(i, 2) cin >> t[i];
  rep(i, 2) cin >> ab[i].first >> ab[i].second;

  sort(all(ab), greater<pair<ll, ll>>());

  ll diff1 = (ab[0].first - ab[1].first) * t[0];
  ll diff2 = (ab[0].second - ab[1].second) * t[1];
  ll diff3 = (ab[0].second * t[1] + diff1) - ab[1].second * t[1];
  if (diff3 == 0) {
    cout << "infinity" << endl;
    return 0;
  }

  // cout << diff1 << " " << diff2 << "  " << diff3 << endl;

  if (diff3 > 0) {
    cout << 0 << endl;
    return 0;
  }

  assert(false);
}


Fixed submission:
/*
これを入れて実行
g++ code.cpp
./a.out
 */

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <stdio.h>
#include <string>
#include <tuple>
#include <unordered_map>
#include <utility>
#include <vector>

#define all(x) (x).begin(), (x).end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using namespace std;
typedef long long ll;
typedef long double ld;

int dy4[4] = {-1, 0, +1, 0};
int dx4[4] = {0, +1, 0, -1};
int dy8[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
int dx8[8] = {0, 1, 1, 1, 0, -1, -1, -1};

const long long INF = 1LL << 60;
const ll MOD = 1e9 + 7;

bool greaterSecond(const pair<int, int> &f, const pair<int, int> &s) {
  return f.second > s.second;
}

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

ll conbinationMemo[100][100];

void cmemoInit() {
  rep(i, 100) {
    rep(j, 100) { conbinationMemo[i][j] = -1; }
  }
}

ll nCr(ll n, ll r) {
  if (conbinationMemo[n][r] != -1)
    return conbinationMemo[n][r];
  if (r == 0 || r == n) {
    return 1;
  } else if (r == 1) {
    return n;
  }
  return conbinationMemo[n][r] = (nCr(n - 1, r) + nCr(n - 1, r - 1));
}

ll nPr(ll n, ll r) {
  r = n - r;
  ll ret = 1;
  for (ll i = n; i >= r + 1; i--)
    ret *= i;
  return ret;
}
//-----------------------ここから-----------
int main(void) {
  vector<ll> t(2);
  vector<pair<ll, ll>> ab(2);
  rep(i, 2) cin >> t[i];
  rep(i, 2) cin >> ab[i].first >> ab[i].second;

  sort(all(ab), greater<pair<ll, ll>>());

  ll diff1 = (ab[0].first - ab[1].first) * t[0];
  ll diff2 = (ab[0].second - ab[1].second) * t[1];
  ll diff3 = (ab[0].second * t[1] + diff1) - ab[1].second * t[1];
  if (diff3 == 0) {
    cout << "infinity" << endl;
    return 0;
  }

  // cout << diff1 << " " << diff2 << "  " << diff3 << endl;

  if (diff3 > 0) {
    cout << 0 << endl;
    return 0;
  }

  if (diff1 % diff3 == 0) {
    cout << abs(diff1 / diff3) * 2 << endl;
  } else {
    cout << abs(diff1 / diff3) * 2 + 1 << endl;
  }
}