Submission #965425

#	Time	Username	Problem	Language	Result	Execution time	Memory
965425		steveonalex	Boat (APIO16_boat)	C++17	9 / 100	393 ms	4840 KiB

boat

#include <bits/stdc++.h>

using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define ALL(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
 
// mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng(1);
ll rngesus(ll l, ll r){return ((ull) rng()) % (r - l + 1) + l;}
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
 
ll LASTBIT(ll mask){return mask & (-mask);}
ll pop_cnt(ll mask){return __builtin_popcountll(mask);}
ll ctz(ll mask){return __builtin_ctzll(mask);}
ll clz(ll mask){return __builtin_clzll(mask);}
ll logOf(ll mask){return 63 - clz(mask);}
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b){a = b; return true;}
        return false;
    }
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b){a = b; return true;}
        return false;
    }
template <class T>
    void printArr(T& a, string separator = " ", string finish = "\n", ostream& out = cout){
        for(auto i: a) out << i << separator;
        out << finish;
    }
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

const long MOD = 1e9 + 7;
ll fast_pow(ll a, ll b){
    ll ans = 1;
    while(b > 0){
        if (b & 1) ans = ans * a % MOD;
        a = a * a % MOD;
        b /= 2;
    }
    return ans;
}
 
ll inverse(ll a){return fast_pow(a, MOD - 2);}
 
const long N = 505;
ll fact[N], ifact[N];
 
void prepare(){
    fact[0] = 1;
    for(long i = 1; i<N; ++i) fact[i] = fact[i-1] * i % MOD;
    ifact[N-1]= inverse(fact[N-1]);
    for(long i = N-1; i>=1; --i) ifact[i-1] = ifact[i] * i % MOD;
}
 
ll C(long n, long k){
    if (k < 0 || k > n) return 0;
    return fact[n] * ifact[k] % MOD * ifact[n - k] % MOD;
}
 
ll eulerCandy(long s, long k){
    return C(s + k - 1, k - 1);
}
 
ll normie(ll a){
    a %= MOD;
    if (a < 0) a += MOD;
    return a;
}

void add(int &a, int b){
    a += b;
    if (a >= MOD) a -= MOD;
}

void sub(int &a, int b){
    a -= b;
    if (a < 0) a += MOD;
}

int dp[N * 2][N], s[N * 2][N];

int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    prepare();

    int n; cin >> n;
    vector<pair<int, int>> a(n);
    for(int i= 0; i<n; ++i) cin >> a[i].first >> a[i].second;

    vector<int> b;
    for(pair<int, int> i: a){
        b.push_back(i.first - 1);
        b.push_back(i.second);
    }
    remove_dup(b);

    vector<pair<int, int>> range;
    range.push_back({0, 0});
    for(int i= 1; i<(int)b.size(); ++i) range.push_back({b[i-1] + 1, b[i]});

    a.insert(a.begin(), {0, 0});

    dp[0][0] = 1;
    for(int i= 0; i <= n; ++i) s[0][i] = 1;
    for(int i= 0; i<range.size(); ++i) s[i][0] = 1;

    for(int layer = 1; layer < (int)range.size(); ++layer){
        int len = range[layer].second - range[layer].first + 1;
        vector<int> fuck(min(n, len) + 1, 1); 
        for(int i = 1; i<(int)fuck.size(); ++i)
            fuck[i] = 1LL * fuck[i-1] * (len - i + 1) % MOD;
        for(int i = 1; i<(int)fuck.size(); ++i) 
            fuck[i] = 1LL * fuck[i] * ifact[i] % MOD;

        vector<int> love(n+1);
        love[1] = len;
        for(int i = 2; i<=n; ++i){
            for(int t = 2; t <= min(fuck.size() - 1, i); ++t){
                add(love[i], 1LL * fuck[t] * C(i - 2, t - 2) % MOD);
            }
        }

        for(int i = 1; i<=n; ++i){
            if (a[i].first > range[layer].first || range[layer].second > a[i].second) continue;
            int sum = s[layer - 1][i - 1];
            int cnt = 0;
            for(int j = i; j<=n; ++j){
                if (a[j].first > range[layer].first || range[layer].second > a[j].second) continue;
                cnt++;
                dp[layer][j] = 1LL * sum * love[cnt] % MOD;
            }
        }
        for(int i = 1; i<=n; ++i){
            s[layer][i] = dp[layer][i];
            add(s[layer][i], s[layer-1][i]);
            add(s[layer][i], s[layer][i-1]);
            sub(s[layer][i], s[layer-1][i-1]);
        }
    }

    int ans = s[range.size() - 1][n];
    sub(ans, 1);

    cout << ans << "\n";
    

    return 0;
}

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:120:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  120 |     for(int i= 0; i<range.size(); ++i) s[i][0] = 1;
      |                   ~^~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42