Submission #221652

#	Time	Username	Problem	Language	Result	Execution time	Memory
221652		ryansee	Skyscraper (JOI16_skyscraper)	C++14	100 / 100	695 ms	146424 KiB

skyscraper

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

#define FAST ios_base::sync_with_stdio(false); cin.tie(0);
#define pb push_back
#define eb emplace_back
#define ins insert
#define f first
#define s second
#define cbr cerr << "hi\n"
#define mmst(x, v) memset((x), v, sizeof ((x)))
#define siz(x) ll(x.size())
#define all(x) (x).begin(), (x).end()
#define lbd(x,y) (lower_bound(all(x),y)-x.begin())
#define ubd(x,y) (upper_bound(all(x),y)-x.begin())
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());    //can be used by calling rng() or shuffle(A, A+n, rng)
inline long long rand(long long x, long long y) { return (rng() % (y+1-x)) + x; } //inclusivesss
string inline to_string(char c) {string s(1,c);return s;} template<typename T> inline T gcd(T a,T b){ return a==0?llabs(b):gcd(b%a,a); }

typedef long long ll; 
typedef long double ld;
#define FOR(i,s,e) for(ll i=s;i<=ll(e);++i)
#define DEC(i,s,e) for(ll i=s;i>=ll(e);--i)
typedef pair<ll,ll>pi; typedef pair<ll,pi>spi; typedef pair<pi,pi>dpi;

#define LLINF ((long long)1e18)
#define INF int(1e9+1e6)
#define MAXN (106)
ll n,L,dp[106][106][2][2][1006],A[106],mod=1e9+7;
int main(){
	FAST
	cin>>n>>L;
	FOR(i,1,n)cin>>A[i];
	sort(A+1,A+n+1);
	if(n==1){
		return cout<<1, 0;
	}
	if(n==2){
		if(A[2]-A[1] <= L) return cout<<2, 0;
		else return cout<<0, 0;
	}
	dp[0][0][0][0][0]=1;
	FOR(i,1,n-1)FOR(c,1,i)FOR(s,0,1)FOR(e,0,1)FOR(l,0,L){
		ll diff=A[i]-A[i-1];
		if(l-diff*((c+1-s-e)*2+s+e)>=0) dp[i][c][s][e][l] += dp[i-1][c+1][s][e][l-diff*((c+1-s-e)*2+s+e)] 
			* (((c+1) * c - (e?c:0) - (s?c:0))%mod)%mod,dp[i][c][s][e][l]%=mod; // +(s&&e)-(s&&e)
		if(l-diff*((c-s-e)*2+s+e)>=0) dp[i][c][s][e][l] += dp[i-1][c][s][e][l-diff*((c-s-e)*2+s+e)] 
			* ((c-s-e)*2+s+e) % mod, dp[i][c][s][e][l]%=mod;
		if(l-diff*((c-1-s-e)*2+s+e)>=0) dp[i][c][s][e][l] += dp[i-1][c-1][s][e][l-diff*((c-1-s-e)*2+s+e)], dp[i][c][s][e][l]%=mod;
		if(s) {
			if(l-diff*((c-e)*2+e)>=0)dp[i][c][s][e][l] += dp[i-1][c][0][e][l-diff*((c-e)*2+e)] * (c-e) % mod, dp[i][c][s][e][l]%=mod;
			if(l-diff*((c-1-e)*2+e)>=0)dp[i][c][s][e][l] += dp[i-1][c-1][0][e][l-diff*((c-1-e)*2+e)] % mod, dp[i][c][s][e][l]%=mod;
		}
		if(e) {
			if(l-diff*((c-s)*2+s)>=0) dp[i][c][s][e][l] += dp[i-1][c][s][0][l-diff*((c-s)*2+s)] * (c-s) % mod, dp[i][c][s][e][l]%=mod;
			if(l-diff*((c-1-s)*2+s)>=0) dp[i][c][s][e][l] += dp[i-1][c-1][s][0][l-diff*((c-1-s)*2+s)] % mod, dp[i][c][s][e][l]%=mod;
		}
		// cerr<<i<<' '<<c<<' '<<s<<' '<<e<<' '<<l<<": "<<dp[i][c][s][e][l]<<'\n';
	}
	ll ans=0;
	// i=n-1, c=2, s=1, e=1, l += diff * 2
	// i=n-1, c=1, s=1, e=0, l += diff
	// i=n-1, c=1, s=0, e=1, l += diff
	FOR(l,0,L){
		ll diff=A[n]-A[n-1];
		if(l-diff*2>=0) ans+=dp[n-1][2][1][1][l-diff*2],ans%=mod;
		if(l-diff>=0) ans+=dp[n-1][1][1][0][l-diff]+dp[n-1][1][0][1][l-diff],ans%=mod;
	}
	cout<<ans<<'\n';
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 80 / 80