oj.uz

Submission #556571

# Submission time Handle Problem Language Result Execution time Memory
556571 2022-05-03T11:19:37 Z InternetPerson10 Boat (APIO16_boat) C++17
36 / 100
 2000 ms 6308 KB 
#include <bits/stdc++.h>
typedef long long ll;

using namespace std;

const ll MOD = 1e9 + 7;

ll modpow(ll n, ll e) {
    if(e == 0) return 1;
    ll x = modpow(n, e/2);
    x *= x; x %= MOD;
    if(e%2) {
        x *= n;
        x %= MOD;
    }
    return x;
}

ll modinv(ll n) {
    return modpow(n, MOD - 2);
}

ll fact[5001];
ll invfact[5001];

ll binom(ll n, ll k) { // Assumes k is quite small
    if(k > n) return 0;
    if(k == n) return 1;
    ll ans = 1;
    if(n-k <= 5000) {
        ans = fact[n];
        ans *= invfact[n-k];
        ans %= MOD;
    }
    else {
        for(ll i = n-k+1; i <= n; i++) {
            ans *= i;
            ans %= MOD;
        }
    }
    ans *= invfact[k];
    ans %= MOD;
    return ans;
}

void precalc() {
    fact[0] = 1;
    for(int i = 1; i <= 5000; i++) {
        fact[i] = (fact[i-1] * i) % MOD;
    }
    for(int i = 0; i <= 5000; i++) {
        invfact[i] = modinv(fact[i]);
    }
}

ll ans[501][1001], pref[501][1001];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    precalc();
    int n;
    cin >> n;
    vector<int> nums(2 * n), a(n+1), b(n+1);
    for(int i = 1; i <= n; i++) {
        cin >> a[i] >> b[i];
        b[i]++;
        nums[2*i - 2] = a[i];
        nums[2*i - 1] = b[i];
    }
    sort(nums.begin(), nums.end());
    nums.resize(unique(nums.begin(), nums.end()) - nums.begin());
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j < nums.size(); j++) {
            if(!(a[i] <= nums[j-1] && nums[j] <= b[i])) {
                continue;
            }
            ll siz = nums[j] - nums[j-1];
            ans[i][j] = siz;
            ans[i][j] += siz * pref[i-1][j-1];
            ans[i][j] %= MOD;
            int g = 1;
            for(int k = i-1; k > 0; k--) {
                if(a[k] <= nums[j-1] && nums[j] <= b[k]) {
                    g++;
                    ll x = siz;
                    for(int l = 2; l <= g; l++) {
                        x *= siz-l+1;
                        x %= MOD;
                        x *= modinv(l);
                        x %= MOD;
                        ans[i][j] += ((x * binom(g-2, l-2)) % MOD) * (1 + pref[k-1][j-1]);
                        ans[i][j] %= MOD;
                    }
                }
            }
        }
        for(int j = 1; j < nums.size(); j++) {
            pref[i][j] = ans[i][j] + pref[i][j-1] + pref[i-1][j] - pref[i-1][j-1];
            pref[i][j] += MOD;
            pref[i][j] %= MOD;
        }
    }
    cout << pref[n][nums.size()-1] << endl;
}

Compilation message

boat.cpp: In function 'int main()':
boat.cpp:74:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   74 |         for(int j = 1; j < nums.size(); j++) {
      |                        ~~^~~~~~~~~~~~~
boat.cpp:98:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   98 |         for(int j = 1; j < nums.size(); j++) {
      |                        ~~^~~~~~~~~~~~~

Subtask #1
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 6096 KB Output is correct
2 Correct 9 ms 6228 KB Output is correct
3 Correct 10 ms 6228 KB Output is correct
4 Correct 10 ms 6132 KB Output is correct
5 Correct 10 ms 6228 KB Output is correct
6 Correct 10 ms 6260 KB Output is correct
7 Correct 10 ms 6228 KB Output is correct
8 Correct 9 ms 6308 KB Output is correct
9 Correct 9 ms 6228 KB Output is correct
10 Correct 9 ms 6248 KB Output is correct
11 Correct 9 ms 6228 KB Output is correct
12 Correct 10 ms 6228 KB Output is correct
13 Correct 10 ms 6228 KB Output is correct
14 Correct 12 ms 6228 KB Output is correct
15 Correct 10 ms 6276 KB Output is correct
16 Correct 7 ms 5076 KB Output is correct
17 Correct 7 ms 5076 KB Output is correct
18 Correct 7 ms 5076 KB Output is correct
19 Correct 6 ms 5076 KB Output is correct
20 Correct 7 ms 5076 KB Output is correct

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 6096 KB Output is correct
2 Correct 9 ms 6228 KB Output is correct
3 Correct 10 ms 6228 KB Output is correct
4 Correct 10 ms 6132 KB Output is correct
5 Correct 10 ms 6228 KB Output is correct
6 Correct 10 ms 6260 KB Output is correct
7 Correct 10 ms 6228 KB Output is correct
8 Correct 9 ms 6308 KB Output is correct
9 Correct 9 ms 6228 KB Output is correct
10 Correct 9 ms 6248 KB Output is correct
11 Correct 9 ms 6228 KB Output is correct
12 Correct 10 ms 6228 KB Output is correct
13 Correct 10 ms 6228 KB Output is correct
14 Correct 12 ms 6228 KB Output is correct
15 Correct 10 ms 6276 KB Output is correct
16 Correct 7 ms 5076 KB Output is correct
17 Correct 7 ms 5076 KB Output is correct
18 Correct 7 ms 5076 KB Output is correct
19 Correct 6 ms 5076 KB Output is correct
20 Correct 7 ms 5076 KB Output is correct
21 Execution timed out 2077 ms 2212 KB Time limit exceeded
22 Halted 0 ms 0 KB -

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 426 ms 1340 KB Output is correct
2 Correct 231 ms 1396 KB Output is correct
3 Correct 357 ms 1452 KB Output is correct
4 Correct 405 ms 1352 KB Output is correct
5 Correct 486 ms 1416 KB Output is correct
6 Correct 1726 ms 1560 KB Output is correct
7 Correct 1760 ms 1384 KB Output is correct
8 Correct 1739 ms 1416 KB Output is correct
9 Correct 1765 ms 1572 KB Output is correct
10 Correct 1738 ms 1352 KB Output is correct
11 Correct 501 ms 1424 KB Output is correct
12 Correct 263 ms 1280 KB Output is correct
13 Correct 382 ms 1388 KB Output is correct
14 Correct 393 ms 1372 KB Output is correct
15 Correct 484 ms 1372 KB Output is correct
16 Correct 314 ms 1228 KB Output is correct
17 Correct 212 ms 1196 KB Output is correct
18 Correct 263 ms 1228 KB Output is correct
19 Correct 213 ms 1228 KB Output is correct
20 Correct 318 ms 1328 KB Output is correct

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 6096 KB Output is correct
2 Correct 9 ms 6228 KB Output is correct
3 Correct 10 ms 6228 KB Output is correct
4 Correct 10 ms 6132 KB Output is correct
5 Correct 10 ms 6228 KB Output is correct
6 Correct 10 ms 6260 KB Output is correct
7 Correct 10 ms 6228 KB Output is correct
8 Correct 9 ms 6308 KB Output is correct
9 Correct 9 ms 6228 KB Output is correct
10 Correct 9 ms 6248 KB Output is correct
11 Correct 9 ms 6228 KB Output is correct
12 Correct 10 ms 6228 KB Output is correct
13 Correct 10 ms 6228 KB Output is correct
14 Correct 12 ms 6228 KB Output is correct
15 Correct 10 ms 6276 KB Output is correct
16 Correct 7 ms 5076 KB Output is correct
17 Correct 7 ms 5076 KB Output is correct
18 Correct 7 ms 5076 KB Output is correct
19 Correct 6 ms 5076 KB Output is correct
20 Correct 7 ms 5076 KB Output is correct
21 Execution timed out 2077 ms 2212 KB Time limit exceeded
22 Halted 0 ms 0 KB -