Submission #102258

#	Time	Username	Problem	Language	Result	Execution time	Memory
102258		jasony123123	Skyscraper (JOI16_skyscraper)	C++11	100 / 100	112 ms	19240 KiB

skyscraper

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,start,end) for(int i=start;i<(int)(end);i++)
#define FORE(i,start,end) for(int i=start;i<=(int)end;i++)
#define RFORE(i,start,end) for(int i = start; i>=end; i--)
#define all(a) a.begin(), a.end()
#define v vector
#define mp make_pair
typedef long long ll;
typedef pair<int, int > pii;
template<class T> void minn(T &a, T b) { a = min(a, b); }
template<class T> void maxx(T &a, T b) { a = max(a, b); }
void io() {
#ifdef LOCAL_PROJECT 
	freopen("input.in", "r", stdin); freopen("output.out", "w", stdout);
#else 
#endif 
	ios_base::sync_with_stdio(false); cin.tie(NULL);
}
/***************************JOI16_skyscraper*************************************/

int N, a[101], L;
int dp[101][101][3][1001];
/*
# ways to assign [i,N] with total abs <= L
given start with g groups, e ends, sum base value
*/
ll f(int i, int g, int e, int sum) {
	sum += (2 * g + e)*(a[i] - a[i - 1]);
	if (sum > L) return 0;
	if (i == N) {
		if (g == 0 && e!=0) return 1;
		else return 0;
	}
	if (dp[i][g][e][sum] == 0) {
		ll ret = 0;
		// join existing group
		if (g > 0 || e > 0) ret += f(i + 1, g, e, sum)*(2 * g + e);
		// make new group
		ret += f(i + 1, g + 1, e, sum)*(g + 1);
		// join two groups or ends
		if (g > 0) ret += f(i + 1, g - 1, e, sum)*(e + g - 1);
		// make new end, by itself
		if (e < 2) ret += f(i + 1, g, e + 1, sum)*(2 - e);
		// make new end, joined with a group
		if (e < 2 && g>0) ret += f(i + 1, g - 1, e + 1, sum)*(2 - e);
		ret %= 1000000007;
		if (ret > 0)
			dp[i][g][e][sum] = ret;
		else
			dp[i][g][e][sum] = -1;
	}
	if (dp[i][g][e][sum] > 0) return dp[i][g][e][sum];
	else return 0;
}

int main() {
	io();
	cin >> N >> L;
	if (N == 1) {
		cout << 1 << "\n";
		return 0;
	}
	FORE(i, 1, N) cin >> a[i];
	sort(a + 1, a + 1 + N);
	cout << f(1, 0, 0, 0) << "\n";
}

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