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답안 #542998

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
542998 2022-03-28T18:22:06 Z fcw Skyscraper (JOI16_skyscraper) C++17
100 / 100
 78 ms 2764 KB 
#include <bits/stdc++.h>
#define st first
#define nd second
using lint = int64_t;
constexpr int mod = int(1e9) + 7;
constexpr int inf = 0x3f3f3f3f;
constexpr int ninf = 0xcfcfcfcf;
constexpr lint linf = 0x3f3f3f3f3f3f3f3f;
const long double pi = acosl(-1.0);
// Returns -1 if a < b, 0 if a = b and 1 if a > b.
int cmp_double(double a, double b = 0, double eps = 1e-9) {
	return a + eps > b ? b + eps > a ? 0 : 1 : -1;
}
using namespace std;

template<unsigned M_> struct modnum {
    static constexpr unsigned M = M_;
    using ll = long long; using ull = unsigned long long; unsigned x;
    constexpr modnum() : x(0U) {}
    constexpr modnum(unsigned x_) : x(x_ % M) {}
    constexpr modnum(int x_) : x(((x_ %= static_cast<int>(M)) < 0) ? (x_ + static_cast<int>(M)) : x_) {}
    constexpr modnum(ull x_) : x(x_ % M) {}
    constexpr modnum(ll x_) : x(((x_ %= static_cast<ll>(M)) < 0) ? (x_ + static_cast<ll>(M)) : x_) {}
    explicit operator int() const { return x; }
    modnum& operator+=(const modnum& a) { x = ((x += a.x) >= M) ? (x - M) : x; return *this; }
    modnum& operator-=(const modnum& a) { x = ((x -= a.x) >= M) ? (x + M) : x; return *this; }
    modnum& operator*=(const modnum& a) { x = unsigned((static_cast<ull>(x) * a.x) % M); return *this; }
    modnum& operator/=(const modnum& a) { return (*this *= a.inv()); }
    modnum operator+(const modnum& a) const { return (modnum(*this) += a); }
    modnum operator-(const modnum& a) const { return (modnum(*this) -= a); }
    modnum operator*(const modnum& a) const { return (modnum(*this) *= a); }
    modnum operator/(const modnum& a) const { return (modnum(*this) /= a); }
    modnum operator+() const { return *this; }
    modnum operator-() const { modnum a; a.x = x ? (M - x) : 0U; return a; }
    modnum pow(ll e) const {
        if (e < 0) return inv().pow(-e);
        modnum x2 = x, xe = 1U;
        for (; e; e >>= 1) {
            if (e & 1) xe *= x2;
            x2 *= x2;
        }
        return xe;
    }
    modnum inv() const {
        unsigned a = x, b = M; int y = 1, z = 0;
        while (a) {
            const unsigned q = (b/a), c = (b - q*a);
            b = a, a = c; const int w = z - static_cast<int>(q) * y;
            z = y, y = w;
        } assert(b == 1U); return modnum(z);
    }
    friend modnum inv(const modnum& a) { return a.inv(); }
    template<typename T> friend modnum operator+(T a, const modnum& b) { return (modnum(a) += b); }
    template<typename T> friend modnum operator-(T a, const modnum& b) { return (modnum(a) -= b); }
    template<typename T> friend modnum operator*(T a, const modnum& b) { return (modnum(a) *= b); }
    template<typename T> friend modnum operator/(T a, const modnum& b) { return (modnum(a) /= b); }
    explicit operator bool() const { return x; }
    friend bool operator==(const modnum& a, const modnum& b) { return a.x == b.x; }
    friend bool operator!=(const modnum& a, const modnum& b) { return a.x != b.x; }
    friend ostream &operator<<(ostream& os, const modnum& a) { return os << a.x; }
    friend istream &operator>>(istream& in, modnum& n) { ull v_; in >> v_; n = modnum(v_); return in; }
};

using mint = modnum<mod>;

int main() {
	cin.tie(nullptr)->sync_with_stdio(false);
	int n, L;
	cin>>n>>L;
	if(n == 1){
		cout<<"1\n";
		return 0;
	}
	vector<int>a(n+1);
	for(int i=0;i<n;i++) cin>>a[i];
	a[n] = 10000;
	sort(a.begin(), a.end());
	vector<vector<array<mint, 3>>>dp(n+1, vector<array<mint, 3>>(L+1)), ndp = dp;
	dp[0][0][0] = 1;
	for(int i=1;i<=n;i++){
		for(int j=0;j<=i;j++){
			for(int k=0;k<=L;k++){
				for(int l=0;l<=2;l++) ndp[j][k][l] = 0;
			}
		}
		for(int j=1;j<=i;j++){
			for(int l=0;l<=2;l++){
				int d = (2*j - l) * (a[i] - a[i-1]);
				for(int k=d;k<=L;k++){
					ndp[j][k][l] += dp[j-1][k-d][l];

					if(l) ndp[j][k][l] += (3 - l) * dp[j-1][k-d][l-1];

					ndp[j][k][l] += (2 * j - l) * dp[j][k-d][l];

					if(l == 1) ndp[j][k][l] += 2 * j * dp[j][k-d][l-1];
					else if(l == 2){
						if(i == n) ndp[j][k][l] += dp[j][k-d][l-1];
						else ndp[j][k][l] += (j - 1) * dp[j][k-d][l-1];
					}

					if(l == 2){
						if(i == n) ndp[j][k][l] += dp[j+1][k-d][l];
						else ndp[j][k][l] += j * (j - 1) * dp[j+1][k-d][l];
					}
					else if(l == 1) ndp[j][k][l] += j * j * dp[j+1][k-d][l];
					else ndp[j][k][l] += j * (j + 1) * dp[j+1][k-d][l];
				}
			}
		}
		swap(dp, ndp);
	}
	mint ans = 0;
	for(int i=0;i<=L;i++) ans += dp[1][i][2];
	cout<<ans<<"\n";
	return 0;
}
/*
[  ]Leu o problema certo???
[  ]Ver se precisa de long long
[  ]Viu o limite dos fors (é n? é m?)
[  ]Tamanho do vetor, será que é 2e5 em vez de 1e5??
[  ]Testar sample
[  ]Testar casos de  borda
[  ]1LL no 1LL << i
[  ]Testar mod (é 1e9+7, mesmo?, será que o mod não ficou negativo?)
*/

Subtask #1
5.0 / 5.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 0 ms 340 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 468 KB Output is correct
10 Correct 1 ms 340 KB Output is correct

Subtask #2
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 340 KB Output is correct
10 Correct 1 ms 340 KB Output is correct

Subtask #3
80.0 / 80.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 0 ms 340 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 468 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 340 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 1 ms 340 KB Output is correct
15 Correct 1 ms 340 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 0 ms 212 KB Output is correct
18 Correct 1 ms 212 KB Output is correct
19 Correct 1 ms 340 KB Output is correct
20 Correct 1 ms 340 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 65 ms 1832 KB Output is correct
23 Correct 72 ms 2764 KB Output is correct
24 Correct 60 ms 2068 KB Output is correct
25 Correct 78 ms 2644 KB Output is correct
26 Correct 56 ms 2260 KB Output is correct
27 Correct 22 ms 852 KB Output is correct
28 Correct 31 ms 980 KB Output is correct
29 Correct 58 ms 1620 KB Output is correct
30 Correct 71 ms 2644 KB Output is correct