Submission #1087227

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087227		mispertion	Boat (APIO16_boat)	C++17	9 / 100	669 ms	2964 KiB

boat

#include <bits/stdc++.h>

using namespace std;    
#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long ll;
#define int ll
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define pb push_back
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define mispertion ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define F first
#define S second
#define getlast(s) (*s.rbegin())
#define debg cout << "OK\n"

const ld PI = 3.1415926535;
const int N = 2e3 + 10;
const int M = 1e5 + 10;
int mod = 1e9+7;
const int infi = INT_MAX;
const ll infl = 2e18;
const int P = 505319;
const ld eps = 1e-9;

int mult(int a, int b){
    return a * 1LL * b % mod;
}

int sum(int a, int b){
    a %= mod;
    b %= mod;
    if(a + b >= mod)
        return a + b - mod;
    if(a + b < 0)
        return a + b + mod;
    return a + b;
}

int binpow(int a, int n){
    if (n == 0)
        return 1;
    if (n % 2 == 1){
        return mult(binpow(a, n - 1), a);
    }
    else{
        auto b = binpow(a, n / 2);
        return mult(b, b);
    }
}

int n, l[N], r[N], sm[N], f[N], fi[N];
vector<int> al[N];

int C(int n, int k){
    return mult(f[n], mult(fi[k], fi[n - k]));
}

void solve(){
    cin >> n;
    vector<int> di = {};
    for(int i = 1; i <= n; i++){
        cin >> l[i] >> r[i];
        di.pb(l[i]);
        di.pb(r[i] + 1);
    }
    di.pb(0);
    sort(all(di));
    di.resize(unique(all(di)) - di.begin());
    sm[0] = 1;
    al[0].pb(1);
    for(int i = 1; i <= n; i++){
        int cur = 0;
        for(int j = 0; j < sz(di) - 1; j++){
            int lr = di[j], rr = di[j + 1] - 1;
            int len = rr - lr + 1;
            if(lr >= l[i] && rr <= r[i]){
                al[j].pb(cur);
                int nsm = 0;
                for(int k = 0; k < sz(al[j]); k++){
                    nsm =sum(nsm, mult(C(sz(al[j]) - k - 1 + len, sz(al[j]) - k), al[j][k]));
                }
                cur = sum(cur, sm[j]);
                sm[j] = nsm;
            }else{
                cur = sum(cur, sm[j]);
            }
        }
    }
    int ans = 0;
    for(int i = 0; i < sz(di) - 1; i++)
        ans = sum(ans, sm[i]);
    cout << sum(ans, -1) << '\n';
}   

signed main(){
    mispertion;
    f[0] = 1;
    for(int i = 1; i < N; i++)
        f[i] = mult(f[i - 1], i);
    for(int i = 0; i < N; i++){
        fi[i] = binpow(f[i], mod - 2);
    }
    int t = 1;
    //cin >> t;
    while (t--){
        solve();
    }
    return 0;
}

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