Submission #441567

#	Time	Username	Problem	Language	Result	Execution time	Memory
441567		dynam1c	Ice Hockey World Championship (CEOI15_bobek)	C++17	100 / 100	531 ms	8524 KiB

bobek

//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

#define endl "\n"
#define all(c) (c).begin(),(c).end()

// when you ponder, divide and conquer

signed main() {
	// freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
	std::ios::sync_with_stdio(false);
	cin.tie(0);
	
	int n;
	ll m;
	cin >> n >> m;
	vector<ll> arr(n);
	for (int i = 0; i < n; i++)
		cin >> arr[i];
	vector<ll> ee(1<<(n/2));
	for (int b = 0; b < 1<<(n/2); b++) {
		ll x = 0;
		for (int l = 0; l < 20; l++) if (b>>l & 1)
			x += arr[l];
		ee[b] = x;
	}
	sort(all(ee));
	ll res = 0;
	for (int b = 0; b < 1<<(n-n/2); b++) {
		ll x = 0;
		for (int l = 0; l < 20; l++) if (b>>l & 1)
			x += arr[n/2+l];
		res += upper_bound(all(ee), m-x) - ee.begin();
	}
	cout << res << endl;
}
/* --- PSolving ---
 * Simplifying (getting rid of variables, conditions, code logic, etc.)
 * Reframing
 * Solving a subtask (subgoal, aux. problem, removing a condition or fixing a parameter, etc.)
 * Inducing
 * Divide and conquer
 * Working backwards
 * Visual intuition
 * !! Reductions don't have to be specializations, they can be generalizations
 */

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10