oj.uz

Submission #556554

# Submission time Handle Problem Language Result Execution time Memory
556554 2022-05-03T10:45:34 Z InternetPerson10 Boat (APIO16_boat) C++17
0 / 100
 473 ms 6240 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 smallinv[2001];

ll binom(ll n, ll k) { // Assumes k is quite small
    ll ans = 1;
    for(ll i = n-k+1; i <= n; i++) {
        ans *= i;
        ans %= MOD;
    }
    for(ll i = 1; i <= k; i++) {
        ans *= modinv(i);
        ans %= MOD;
    }
    return ans;
}

void precalc() {
    smallinv[0] = 1;
    for(int i = 1; i <= 2000; i++) {
        smallinv[i] = (smallinv[i-1] * i) % MOD;
    }
    for(int i = 0; i <= 2000; i++) {
        smallinv[i] = modinv(smallinv[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])) {
                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;
                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++;
                    ans[i][j] += (binom(siz+1, g) - (siz+1) + MOD) * (1 + pref[k-1][j-1]);
                    ans[i][j] %= MOD;
                }
            }
            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:66:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |         for(int j = 1; j < nums.size(); j++) {
      |                        ~~^~~~~~~~~~~~~

Subtask #1
0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 6100 KB Output is correct
2 Correct 9 ms 6108 KB Output is correct
3 Correct 9 ms 6176 KB Output is correct
4 Correct 8 ms 6088 KB Output is correct
5 Correct 9 ms 6072 KB Output is correct
6 Correct 8 ms 6228 KB Output is correct
7 Correct 9 ms 6228 KB Output is correct
8 Correct 9 ms 6228 KB Output is correct
9 Correct 13 ms 6228 KB Output is correct
10 Correct 9 ms 6188 KB Output is correct
11 Correct 8 ms 6228 KB Output is correct
12 Correct 8 ms 6236 KB Output is correct
13 Correct 8 ms 6236 KB Output is correct
14 Correct 8 ms 6240 KB Output is correct
15 Correct 8 ms 6240 KB Output is correct
16 Incorrect 7 ms 4948 KB Output isn't correct
17 Halted 0 ms 0 KB -

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 6100 KB Output is correct
2 Correct 9 ms 6108 KB Output is correct
3 Correct 9 ms 6176 KB Output is correct
4 Correct 8 ms 6088 KB Output is correct
5 Correct 9 ms 6072 KB Output is correct
6 Correct 8 ms 6228 KB Output is correct
7 Correct 9 ms 6228 KB Output is correct
8 Correct 9 ms 6228 KB Output is correct
9 Correct 13 ms 6228 KB Output is correct
10 Correct 9 ms 6188 KB Output is correct
11 Correct 8 ms 6228 KB Output is correct
12 Correct 8 ms 6236 KB Output is correct
13 Correct 8 ms 6236 KB Output is correct
14 Correct 8 ms 6240 KB Output is correct
15 Correct 8 ms 6240 KB Output is correct
16 Incorrect 7 ms 4948 KB Output isn't correct
17 Halted 0 ms 0 KB -

Subtask #3
0 / 27.0

# Verdict Execution time Memory Grader output
1 Incorrect 473 ms 1328 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 6100 KB Output is correct
2 Correct 9 ms 6108 KB Output is correct
3 Correct 9 ms 6176 KB Output is correct
4 Correct 8 ms 6088 KB Output is correct
5 Correct 9 ms 6072 KB Output is correct
6 Correct 8 ms 6228 KB Output is correct
7 Correct 9 ms 6228 KB Output is correct
8 Correct 9 ms 6228 KB Output is correct
9 Correct 13 ms 6228 KB Output is correct
10 Correct 9 ms 6188 KB Output is correct
11 Correct 8 ms 6228 KB Output is correct
12 Correct 8 ms 6236 KB Output is correct
13 Correct 8 ms 6236 KB Output is correct
14 Correct 8 ms 6240 KB Output is correct
15 Correct 8 ms 6240 KB Output is correct
16 Incorrect 7 ms 4948 KB Output isn't correct
17 Halted 0 ms 0 KB -