Submission #242168

#	Time	Username	Problem	Language	Result	Execution time	Memory
242168		WhaleVomit	Boat (APIO16_boat)	C++14	100 / 100	1343 ms	16632 KiB

boat

#include <bits/stdc++.h>
using namespace std;

#define f first
#define s second
#define pb push_back
#define mp make_pair
#define all(v) v.begin(), v.end()
#define sz(v) (int)v.size()

#define MOO(i, a, b) for(int i=a; i<b; i++)
#define M00(i, a) for(int i=0; i<a; i++)
#define MOOd(i,a,b) for(int i = (b)-1; i >= a; i--)
#define M00d(i,a) for(int i = (a)-1; i>=0; i--)

#define FAST ios::sync_with_stdio(0); cin.tie(0);
#define finish(x) return cout << x << '\n', 0;
#define dbg(x) cerr << ">>> " << #x << " = " << x << "\n";
#define _ << " _ " <<

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int,int> pi;
typedef pair<ld,ld> pd;
typedef complex<ld> cd;

const ll MOD = 1000000007;
const int MAX_N = 505;
int n;
pi arr[MAX_N];
ll fact[MAX_N];
ll factor[MAX_N*4][MAX_N];
vector<ll> dp[4*MAX_N];

bool cont(pi p1, pi p2) {
    return p2.f <= p1.f && p1.s <= p2.s;
}

int len(pi p) {
    return p.s - p.f + 1;
}

ll mpow(ll base, ll exp) {
    if(exp == 0) return 1;
    ll res = mpow(base, exp/2);
    res *= res; res %= MOD;
    if(exp%2 == 1) {
        res *= base; res %= MOD;
    }
    return res;
}

ll inv(ll k) {
    return mpow(k, MOD-2);
}

ll getSum(int j, vector<ll>& v) {
    ll res = 0;
    int ctr = 0;
    M00d(idx, sz(v)) {
        if(v[idx] == 0) continue;
        ll val = (v[idx] * factor[j][ctr]) % MOD;
        res += val;
        res %= MOD;
        ctr++;
    }
    return res;
}

int main() { FAST
    fact[0] = 1;
    MOO(i, 1, MAX_N) fact[i] = (fact[i-1] * i) % MOD;
    cin >> n;
    M00(i, n) cin >> arr[i].f >> arr[i].s;
    vi idxs;
    idxs.pb(0);
    M00(i, n) {
        idxs.pb(arr[i].f);
        idxs.pb(arr[i].s);
    }
    sort(all(idxs));
    idxs.erase(unique(all(idxs)), idxs.end());
    vector<pi> intervals;
    intervals.pb(mp(0,0));
    MOO(i, 1, sz(idxs)) {
        pi p = mp(idxs[i-1]+1, idxs[i]-1);
        if(p.f <= p.s) intervals.pb(p);
        intervals.pb(mp(idxs[i], idxs[i]));
    }
    sort(all(intervals));
    M00(i, sz(intervals)) {
        ll x = len(intervals[i]);
        ll cur = 1;
        M00(j, MAX_N-1) {
            cur *= x+j; cur %= MOD;
            factor[i][j] = (cur * inv(fact[j+1])) % MOD;
        }
    }

    dp[0].pb(1);
    MOO(i, 1, sz(intervals)) {
        if(cont(intervals[i], arr[0])) dp[i].pb(1);
        else dp[i].pb(0);
    }
    MOO(i, 1, n) {
        ll cursum = 0;
        M00(j, sz(intervals)) {
            ll add = getSum(j, dp[j]);
            if(cont(intervals[j], arr[i])) {
                dp[j].pb(cursum);
            } else {
                dp[j].pb(0);
            }
            cursum += add;
            cursum %= MOD;
        }
    }
    ll ans = MOD-1;
    M00(i, sz(intervals)) {
        ans += getSum(i, dp[i]);
        ans %= MOD;
    }
    finish(ans);
}

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