Submission #3235838

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

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

#define each(i,a) for (auto&& i : a)
#define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
#define RFOR(i,a,b) for (ll i=(b)-1,__last_##i=(a);i>=__last_##i;i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define __GET_MACRO3(_1, _2, _3, NAME, ...) NAME
#define rep(...) __GET_MACRO3(__VA_ARGS__, FOR, REP)(__VA_ARGS__)
#define rrep(...) __GET_MACRO3(__VA_ARGS__, RFOR, RREP)(__VA_ARGS__)
#define pb push_back
#define eb emplace_back
#define all(a) (a).begin(),(a).end()
#define chmin(x,v) x = min(x, v)
#define chmax(x,v) x = max(x, v)

const ll linf = 1e18;
const double eps = 1e-12;
const double pi = acos(-1);

template<typename T>
istream& operator>>(istream& is, vector<T>& vec) {
  each(x,vec) is >> x;
  return is;
}
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& vec) {
  rep(i,vec.size()) {
    if (i) os << " ";
    os << vec[i];
  }
  return os;
}
template<typename T>
ostream& operator<<(ostream& os, const vector< vector<T> >& vec) {
  rep(i,vec.size()) {
    if (i) os << endl;
    os << vec[i];
  }
  return os;
}

const ll mod = 1e9+7;
// SegmentTree<int> seg(n, 0x7FFFFFFF, [](int a, int b){return min(a, b);});
template <typename T>
class SegmentTree {
  using func_t = function<T(T, T)>;
  const int n;
  const T id;
  func_t merge;
  vector<T> data;
  T sub(int l, int r, int node, int lb, int ub) {
    if (ub <= l || r <= lb) return id;
    if (l <= lb && ub <= r) return data[node];
    T vl = sub(l, r, node * 2 + 0, lb, (lb + ub) / 2);
    T vr = sub(l, r, node * 2 + 1, (lb + ub) / 2, ub);
    return merge(vl, vr);
  }
  int size(int n) {
    int res;
    for (res = 1; res < n; res <<= 1);
    return res;
  }
public:
  SegmentTree(int n, T id, func_t merge) :
    n(size(n)), id(id), merge(merge), data(size(n) * 2, id) {}
  void update(int p, T val) {
    assert (0 <= p && p < n);
    p += n;
    data[p] = val;
    while (p /= 2) {
      int l = p * 2, r = p * 2 + 1;
      data[p] = merge(data[l], data[r]);
    }
  }
  T find(int l, int r) {
    return sub(l, r, 1, 0, n);
  }
};


int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  ll n; cin >> n;
  vector<P> v;
  v.eb(-100000, -100000+1);
  rep(i, n) {
    ll x, d; cin >> x >> d;
    v.eb(x-d, x+d+1);
  }
  n = v.size();
  const ll m = 2100;
  vector<SegmentTree<ll>> dp(2, SegmentTree<ll>(m, 0, [](ll a, ll b) { return (a + b) % mod; }));
  dp[0].update(0, 1);
  rep(i, 1, n) {
    ll l, r; tie(l, r) = v[i];
    rep(j, r-l) {
      ll pos = min(v[i-1].second, max(l+j, v[i-1].first)) - v[i-1].first;
      assert(0 <= pos && pos <= v[i-1].second - v[i-1].first && pos <= m);
      ll val = dp[i+1&1].find(0, pos);
      // cout << pos << " " << j << " " << val << endl;
      dp[i&1].update(j, val);
    }
  }
  cout << dp[(n-1)&1].find(0, m) << endl;
}

Submission Info

Judge Result