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답안 #542995

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
542995 2022-03-28T17:59:05 Z fcw Skyscraper (JOI16_skyscraper) C++17
100 / 100
 94 ms 2712 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+2, 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 k=0;k<=L;k++){
				for(int l=0;l<=2;l++){
					int d = (2 * j - l) * (a[i] - a[i-1]);
					if(k < d || i + j + 1 - l > n) continue;
					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 if(j > 1) 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 k=0;k<=L;k++) ans += dp[1][k][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 1 ms 340 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 1 ms 328 KB Output is correct
8 Correct 1 ms 324 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 1 ms 340 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 1 ms 340 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 1 ms 328 KB Output is correct
8 Correct 1 ms 324 KB Output is correct
9 Correct 1 ms 468 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 1 ms 340 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 324 KB Output is correct
22 Correct 57 ms 1860 KB Output is correct
23 Correct 94 ms 2672 KB Output is correct
24 Correct 73 ms 2100 KB Output is correct
25 Correct 88 ms 2704 KB Output is correct
26 Correct 70 ms 2328 KB Output is correct
27 Correct 29 ms 852 KB Output is correct
28 Correct 36 ms 1100 KB Output is correct
29 Correct 58 ms 1616 KB Output is correct
30 Correct 86 ms 2712 KB Output is correct