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Submission #23486

# Submission time Handle Problem Language Result Execution time Memory
23486 2017-05-10T11:16:32 Z Nirjhor Boat (APIO16_boat) C++14
9 / 100
 803 ms 10280 KB 
#include <bits/stdc++.h> 

using namespace std;

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

const int N = 505;
const int M = 1005;
const int MOD = 1e9 + 7;

int n, m;
ll a[N], b[N];
ll dp[N][M];
vector <pii> v;
ll x[M], y[M];
vector <int> z[M];
int sz[M];
ll wide[M];
int counter = 1;
ll comb[M][N];
ll inverse[N];

ll bigMod (ll a, ll e) {
  if (e == -1) e = MOD - 2;
  ll r = 1ll; while (e) {
    if (e & 1) r = (r * a) % MOD;
    a = (a * a) % MOD;
    e >>= 1;
  }
  return r;
}

ll call (int at, int range) {
  if (at > n or range > m) return 1;
  if (dp[at][range] != -1) return dp[at][range];
  int pos = 0;
  while (pos < sz[range] and z[range][pos] < at) {
    ++pos;
  }
  ll ret = call(at, range + 1);
  for (int i = pos; i < sz[range]; ++i) {
    int rem = i - pos, cur = z[range][i];
    // cout << rem << " comb ---> " << comb[range][rem] << endl;
    ll add = (comb[range][rem] * call(cur + 1, range + 1)) % MOD;
    ret += add, ret %= MOD;
  }
  return dp[at][range] = ret;
}

ll nCr (ll n, ll r) {
  if (n < r or n < 0 or r < 0) return 0;
  ll res = 1ll;
  for (ll i = n; i >= n - r + 1; --i) {
    res *= i, res %= MOD;
  }
  for (ll i = 1; i <= r; ++i) {
    res *= inverse[i];
    res %= MOD;
  }
  return res;
}

int main (int argc, char const *argv[]) {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) {
    scanf("%lld %lld", a + i, b + i);
    v.push_back({a[i], 0});
    v.push_back({b[i], 1});
  }
  sort(v.begin(), v.end());
  for (int i = 1; i < n + n; ++i) {
    int one = v[i - 1].second, two = v[i].second;
    int l = v[i - 1].first, r = v[i].first;
    if (!one and !two) {
      --r, ++counter;
      if (l >= r) x[++m] = l, y[m] = r;
    } else if (!one and two) {
      --counter;
      if (l >= r) x[++m] = l, y[m] = r;
    } else if (one and two) {
      ++l, --counter;
      if (l >= r) x[++m] = l, y[m] = r; 
    } else {
      ++l;
      if (counter and l >= r) x[++m] = l, y[m] = r;
      ++counter;
    }
  }
  // for (int i = 1; i <= m; ++i) {
  //   cout << x[i] << " " << y[i] << endl;
  // }
  for (int i = 1; i <= m; ++i) {
    for (int j = 1; j <= n; ++j) {
      if (a[j] <= x[i] and y[i] <= b[j]) {
        z[i].push_back(j);
        ++sz[i];
      }
    }
    wide[i] = y[i] - x[i] + 1;
  } 
  for (int i = 1; i < N; ++i) {
    inverse[i] = bigMod(i, -1);
  }
  for (int i = 1; i <= m; ++i) {
    for (int j = 0; j <= n; ++j) {
      comb[i][j] = nCr(wide[i] + j, j + 1);
    }
  }
  // for (int i = 1; i <= m; ++i) {
  //   cout << i << " --> ";
  //   for (int j : z[i]) cout << j << " ";
  //   cout << endl;
  // } 
  memset(dp, -1, sizeof dp);
  // for (int i = 1; i <= n; ++i) {
  //   for (int j = 1; j <= m; ++j) {
  //     cout << "(" << i << ", " << j << ") ---> " << call(i, j) << endl;
  //   }
  // }
  ll ans = call(1, 1) + MOD - 1;
  printf("%lld\n", ans % MOD);
  return 0;
}

Compilation message

boat.cpp: In function 'int main(int, const char**)':
boat.cpp:65:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
                  ^
boat.cpp:67:37: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld %lld", a + i, b + i);
                                     ^

Subtask #1
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 793 ms 10016 KB Output is correct
2 Correct 793 ms 10016 KB Output is correct
3 Correct 793 ms 10016 KB Output is correct
4 Correct 799 ms 10016 KB Output is correct
5 Correct 793 ms 10016 KB Output is correct
6 Correct 803 ms 10016 KB Output is correct
7 Correct 776 ms 10016 KB Output is correct
8 Correct 783 ms 10016 KB Output is correct
9 Correct 799 ms 10016 KB Output is correct
10 Correct 793 ms 10016 KB Output is correct
11 Correct 793 ms 10016 KB Output is correct
12 Correct 783 ms 10016 KB Output is correct
13 Correct 786 ms 10016 KB Output is correct
14 Correct 793 ms 10016 KB Output is correct
15 Correct 789 ms 10016 KB Output is correct
16 Correct 159 ms 10148 KB Output is correct
17 Correct 166 ms 10148 KB Output is correct
18 Correct 159 ms 10148 KB Output is correct
19 Correct 156 ms 10148 KB Output is correct
20 Correct 159 ms 10148 KB Output is correct

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 793 ms 10016 KB Output is correct
2 Correct 793 ms 10016 KB Output is correct
3 Correct 793 ms 10016 KB Output is correct
4 Correct 799 ms 10016 KB Output is correct
5 Correct 793 ms 10016 KB Output is correct
6 Correct 803 ms 10016 KB Output is correct
7 Correct 776 ms 10016 KB Output is correct
8 Correct 783 ms 10016 KB Output is correct
9 Correct 799 ms 10016 KB Output is correct
10 Correct 793 ms 10016 KB Output is correct
11 Correct 793 ms 10016 KB Output is correct
12 Correct 783 ms 10016 KB Output is correct
13 Correct 786 ms 10016 KB Output is correct
14 Correct 793 ms 10016 KB Output is correct
15 Correct 789 ms 10016 KB Output is correct
16 Correct 159 ms 10148 KB Output is correct
17 Correct 166 ms 10148 KB Output is correct
18 Correct 159 ms 10148 KB Output is correct
19 Correct 156 ms 10148 KB Output is correct
20 Correct 159 ms 10148 KB Output is correct
21 Incorrect 363 ms 10280 KB Output isn't correct
22 Halted 0 ms 0 KB -

Subtask #3
0 / 27.0

# Verdict Execution time Memory Grader output
1 Incorrect 3 ms 10016 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 793 ms 10016 KB Output is correct
2 Correct 793 ms 10016 KB Output is correct
3 Correct 793 ms 10016 KB Output is correct
4 Correct 799 ms 10016 KB Output is correct
5 Correct 793 ms 10016 KB Output is correct
6 Correct 803 ms 10016 KB Output is correct
7 Correct 776 ms 10016 KB Output is correct
8 Correct 783 ms 10016 KB Output is correct
9 Correct 799 ms 10016 KB Output is correct
10 Correct 793 ms 10016 KB Output is correct
11 Correct 793 ms 10016 KB Output is correct
12 Correct 783 ms 10016 KB Output is correct
13 Correct 786 ms 10016 KB Output is correct
14 Correct 793 ms 10016 KB Output is correct
15 Correct 789 ms 10016 KB Output is correct
16 Correct 159 ms 10148 KB Output is correct
17 Correct 166 ms 10148 KB Output is correct
18 Correct 159 ms 10148 KB Output is correct
19 Correct 156 ms 10148 KB Output is correct
20 Correct 159 ms 10148 KB Output is correct
21 Incorrect 363 ms 10280 KB Output isn't correct
22 Halted 0 ms 0 KB -