Problem p03744 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#if __cplusplus >= 201103L
#include <array>
#include <forward_list>
#include <initializer_list>
#include <tuple>

#define cauto const auto &
#else

#endif

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

typedef vector<int> vint;
typedef vector<vector<int>> vvint;
typedef vector<long long> vll;
typedef vector<vector<long long>> vvll;

#define VV(T) vector<vector<T>>

template <class T>
void initvv(vector<vector<T>> &v, int a, int b, const T &t = T()) {
  v.assign(a, vector<T>(b, t));
}

template <class F, class T> void convert(const F &f, T &t) {
  stringstream ss;
  ss << f;
  ss >> t;
}

#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define _rep(i, n) _rep2((i), 0, (n))
#define _rep2(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(...) GET_MACRO(__VA_ARGS__, _rep2, _rep)(__VA_ARGS__)
#define ALL(v) (v).begin(), (v).end()
#define PB push_back
#define fi first
#define se second
#define mkp make_pair
#define DEBUG
#ifdef DEBUG
#define dump(x) cout << #x << " = " << (x) << endl;
#define debug(x)                                                               \
  cout << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \
       << " " << __FILE__ << endl;
#else
#define dump(x)
#define debug(x)
#endif

#define MOD 1000000007LL
#define EPS 1e-8
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define maxs(x, y) x = max(x, y)
#define mins(x, y) x = min(x, y)

void mainmain() {
  int n;
  ll L;
  cin >> n >> L;
  long double ans;
  deque<pair<long double, int>> q;
  {
    long double t;
    int v;
    cin >> t >> v;
    cout << t << endl;
    ans = t * v;
    q.push_back(mkp(t, v));
  }
  rep(i, 1, n) {
    long double t;
    int v;
    cin >> t >> v;
    int tv = v;
    while (1) {
      auto x = q.back();
      if (tv == x.se) {
        ans -= x.fi * x.se;
        q.pop_back();
        break;
      } else if (tv < x.se) {
        ans -= x.fi * tv;
        q.back().se -= tv;
        break;
      } else {
        ans -= x.fi * x.se;
        q.pop_back();
      }
    }
    ans += t * v;
    cout << ans / L << endl;
    while (1) {
      if (q.size() == 0) {
        q.push_front(mkp(t, v));
        break;
      }
      auto x = q.front();
      if (t <= x.fi) {
        t = (t * v + x.fi * x.se) / (v + x.se);
        v += x.se;
        q.pop_front();
      } else {
        q.push_front(mkp(t, v));
        break;
      }
    }
    // cout<<"hoge "<<endl;
    // for(auto x: q){
    // 	cout<<x.fi<<" "<<x.se<<endl;
    // }
    // cout<<endl;
  }
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(20);
  mainmain();
}

Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#if __cplusplus >= 201103L
#include <array>
#include <forward_list>
#include <initializer_list>
#include <tuple>

#define cauto const auto &
#else

#endif

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

typedef vector<int> vint;
typedef vector<vector<int>> vvint;
typedef vector<long long> vll;
typedef vector<vector<long long>> vvll;

#define VV(T) vector<vector<T>>

template <class T>
void initvv(vector<vector<T>> &v, int a, int b, const T &t = T()) {
  v.assign(a, vector<T>(b, t));
}

template <class F, class T> void convert(const F &f, T &t) {
  stringstream ss;
  ss << f;
  ss >> t;
}

#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define _rep(i, n) _rep2((i), 0, (n))
#define _rep2(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(...) GET_MACRO(__VA_ARGS__, _rep2, _rep)(__VA_ARGS__)
#define ALL(v) (v).begin(), (v).end()
#define PB push_back
#define fi first
#define se second
#define mkp make_pair
#define DEBUG
#ifdef DEBUG
#define dump(x) cout << #x << " = " << (x) << endl;
#define debug(x)                                                               \
  cout << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \
       << " " << __FILE__ << endl;
#else
#define dump(x)
#define debug(x)
#endif

#define MOD 1000000007LL
#define EPS 1e-8
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define maxs(x, y) x = max(x, y)
#define mins(x, y) x = min(x, y)

void mainmain() {
  int n;
  ll L;
  cin >> n >> L;
  long double ans;
  deque<pair<long double, int>> q;
  {
    long double t;
    int v;
    cin >> t >> v;
    cout << t << endl;
    ans = t * v;
    q.push_back(mkp(t, v));
  }
  rep(i, 1, n) {
    long double t;
    int v;
    cin >> t >> v;
    int tv = v;
    while (1) {
      auto x = q.back();
      if (tv == x.se) {
        ans -= x.fi * x.se;
        q.pop_back();
        break;
      } else if (tv < x.se) {
        ans -= x.fi * tv;
        q.back().se -= tv;
        break;
      } else {
        ans -= x.fi * x.se;
        tv -= x.se;
        q.pop_back();
      }
    }
    ans += t * v;
    cout << ans / L << endl;
    while (1) {
      if (q.size() == 0) {
        q.push_front(mkp(t, v));
        break;
      }
      auto x = q.front();
      if (t <= x.fi) {
        t = (t * v + x.fi * x.se) / (v + x.se);
        v += x.se;
        q.pop_front();
      } else {
        q.push_front(mkp(t, v));
        break;
      }
    }
    // cout<<"hoge "<<endl;
    // for(auto x: q){
    // 	cout<<x.fi<<" "<<x.se<<endl;
    // }
    // cout<<endl;
  }
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(20);
  mainmain();
}