Submission #417887

#	Time	Username	Problem	Language	Result	Execution time	Memory
417887		erfanmir	Boat (APIO16_boat)	C++17	100 / 100	816 ms	4480 KiB

boat

// In the name of god

#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 

using namespace std;
using namespace __gnu_pbds; 

template < class T > using ordered_set = tree < T , null_type , less < T > , rb_tree_tag , tree_order_statistics_node_update >;
  
typedef long long                   ll;
typedef long double                 ld;
typedef pair<int,int>               pii;
typedef pair<ll,ll>                 pll;
#define all(x)                      (x).begin(),(x).end()
#define lc(x)                       (x) << 1
#define rc(x)                       (x) << 1 | 1
#define F                           first
#define S                           second
#define fast_io                     ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io                     freopen("in.txt" , "r+" , stdin) ; freopen("out.txt" , "w+" , stdout);
#define mp                          make_pair
ll poww(ll a, ll b, ll md) {
    ll ans = 1;
    for(; b; b >>= 1, a = a * a % md){
        if(b & 1){
            ans = ans * a % md;
        }
    }
    return ans % md;
}

const int MAXN = 1000 + 10;
const int MAXLG = 18;
const int MOD = 1e9 + 7;
const int MOD2 = 998244353;
const ll INF = 8e18;
int n, a[MAXN], b[MAXN];
vector<int> vec;
ll dp[MAXN][MAXN], x[MAXN], ans, inv[MAXN];

int main()
{
    scanf("%d", &n);
    for(int i = 0; i <= n; i++){
        inv[i] = poww(i, MOD - 2, MOD);
    }
    for(int i = 1; i <= n; i++){
        scanf("%d %d", a + i, b + i);
        b[i]++;
        vec.push_back(b[i]);
        vec.push_back(a[i]);
    }
    sort(all(vec));
    vec.erase(unique(all(vec)), vec.end());
    for(int i = 1; i < (int)vec.size(); i++){
        x[i] = vec[i] - vec[i - 1];
    }
    for(int i = 1; i <= n; i++){
        a[i] = lower_bound(all(vec), a[i]) - vec.begin();
        b[i] = lower_bound(all(vec), b[i]) - vec.begin();
    }
    for(int i = 0; i < (int)vec.size(); i++){
        dp[0][i] = 1;
    }
    for(int i = 1; i <= n; i++){
        for(int j = 1; j < (int)vec.size(); j++){
            if(!(a[i] < j && b[i] >= j)){
                continue;
            }
            ll tmp = x[j], kmp = x[j], vlc = 1;
            for(int k = i - 1; k >= 0; k--){
                dp[i][j] += (dp[k][j - 1] * tmp) % MOD;
                dp[i][j] %= MOD;
                if(a[k] < j && b[k] >= j){
                    kmp++;
                    vlc++;
                    kmp %= MOD;
                    vlc %= MOD;
                    tmp *= (kmp * inv[vlc]) % MOD;
                    tmp %= MOD;
                }
            }
            //printf(":: %d %d %lld\n", i, j, dp[i][j]); 
        }
        for(int j = 1; j < (int)vec.size();j++){
            dp[i][j] += dp[i][j - 1];
            dp[i][j] %= MOD;
        }
    }
    for(int i = 1; i <= n; i++){
        ans += dp[i][(int)vec.size() - 1];
        ans %= MOD;
    }
    printf("%lld\n", ans);
}

Compilation message (stderr)

boat.cpp:3: warning: ignoring '#pragma comment ' [-Wunknown-pragmas]
    3 | #pragma comment(linker, "/stack:200000000")
      | 
boat.cpp: In function 'int main()':
boat.cpp:47:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
boat.cpp:52:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |         scanf("%d %d", a + i, b + i);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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