Submission #50214

#	Time	Username	Problem	Language	Result	Execution time	Memory
50214		mra2322001	Boat (APIO16_boat)	C++14	9 / 100	561 ms	8420 KiB

boat

#include <bits/stdc++.h>
#define f0(i, n) for(int i=(0); i<(n); i++)
#define f1(i, n) for(int i=(1); i<=(n); i++)
#define x first
#define y second
#define mod 1000000007

using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
const int N = 502;

int n;
pii a[N];

void sub1(){
    vector <int> f(n + 3, 0);
    f1(i, n){
        f[i] = 1;
        for(int j = i - 1; j >= 1; j--){
            if(a[j].x < a[i].x){
                f[i] = (f[i] + f[j])%mod;
            }
        }
    }
    int res = 0; /// phai co it nhat 1 tau gui
    f1(i, n) res = (res + f[i])%mod;
    cout << res;
    exit(0);
}

void sub2(){
    vector <vector <int> > f;
    f.resize(n + 1);
    f1(i, n){
        f[i].resize((a[i].y - a[i].x + 2), 0);
    }
    f1(i, n){
        int sz = a[i].y - a[i].x + 1;
        f0(j, sz){
            f[i][j] = 1;
            if(j != 0) f[i][j] = (f[i][j] + f[i][j - 1])%mod;
            for(int k = i - 1; k >= 1; k--){
                int x = a[i].x + j, y = -1;
                if(x > a[k].y) y = a[k].y - a[k].x;
                else y = x - a[k].x - 1;
                f[i][j] = (f[i][j] + f[k][y])%mod;
            }
        }
    }
    int res = 0;
    f1(i, n){
        int sz = a[i].y - a[i].x + 1;
        res = (res + f[i][sz - 1])%mod;
    }
    cout << res;
    exit(0);
}

ll d[N*4], cnt = 0;
ll f[N][N*4];
void sub3(){
    f1(i, n){
        d[++cnt] = a[i].x; d[++cnt] = a[i].y;
        d[++cnt] = a[i].x - 1; d[++cnt] = a[i].y + 1;
    }
    sort(d + 1, d + cnt + 1);
    f1(i, n){
        f1(j, cnt - 1){
            f[i][j] = f[i][j - 1];
            if(d[j - 1] >= a[i].x && d[j] <= a[i].y){
            if(d[j] + 1 >= a[i].x && d[j + 1] <= a[i].y && d[j] != d[j + 1]){
                int vt = lower_bound(d + 1, d + cnt + 1, d[j] + 1) - d;
                vt -= 2;
                for(int k = i - 1; k >= 1; k--){
                    if(vt > 0){
                        f[i][j] = ( f[i][j] + (d[j + 1] - d[j])*1ll*(f[k][vt]))%mod;
                    }
                }
                f[i][j] = (f[i][j] + (d[j + 1] - d[j]))%mod;
            }
            }
            else{
                if(d[j] >= a[i].x && d[j + 1] <= a[i].y){
                int vt = lower_bound(d + 1, d + cnt + 1, d[j]) - d;
                vt -= 2;
                for(int k = i - 1; k >= 1; k--){
                    if(vt > 0){
                        f[i][j] = ( f[i][j] + (d[j + 1] - d[j] + 1)*1ll*(f[k][vt]))%mod;
                    }
                }
                f[i][j] = (f[i][j] + (d[j + 1] - d[j] + 1))%mod;
            }
            }
        }
    }
    int res = 0;
    f1(i, n) (res = res + f[i][cnt - 1])%mod;
    cout << (res + mod)%mod;
    exit(0);
}

main(){
    ios_base::sync_with_stdio(0);
 
    bool giong = 1; ll dem = 0;
    cin >> n;
    f1(i, n){
        cin >> a[i].x >> a[i].y;
        if(a[i].x != a[i].y) giong = 0;
        dem += (a[i].y - a[i].x + 1);
    }
    if(giong) sub1();
    ///if(dem <= 1e6 + 560) sub2();
    sub3();
}

Compilation message (stderr)

boat.cpp: In function 'void sub3()':
boat.cpp:98:41: warning: value computed is not used [-Wunused-value]
     f1(i, n) (res = res + f[i][cnt - 1])%mod;
                                         ^
boat.cpp: At global scope:
boat.cpp:103:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^

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