Submission #73188193

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Source Code Expand

#include <bits/stdc++.h>
#define ll long long
const ll N = 1e7 + 5, MOD = 1e9 + 7, inf = 2e18;
using namespace std;
int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
char di[] = {'R', 'L', 'D', 'U'};
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;

void Ebraam() {
    ios_base::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
#ifndef ONLINE_JUDGE
    freopen("Input.txt", "r", stdin);
    freopen("Output.txt", "w", stdout);
#endif
}

void solve() {
    ll n, m;
    cin >> n >> m;
    vector<ll> v(n);
    for (int i = 0; i < n; i++) {
        cin >> v[i];
    }
    vector<ll> l, r;
    int x = n / 2, z = n - x;
    for (int i = 0; i < (1 << x); i++) {
        ll sum = 0;
        for (int j = 0; j < x; j++) {
            if ((i >> j & 1))sum += v[j];
        }
        if (sum <= m)l.push_back(sum);
    }
    for (int msk = 0; msk < (1 << z); msk++) {
        ll sum = 0;
        for (int i = 0; i < z; i++) {
            if ((msk >> i & 1))sum += v[x + i];
        }
        if (sum <= m)r.push_back(sum);
    }
    ll ans = 0;
    sort(r.begin(), r.end());
    for (ll d: l) {
        ans += upper_bound(r.begin(), r.end(), m - d) - lower_bound(r.begin(), r.end(), m - d);
    }
    cout << ans;
}

int main() {
    Ebraam();
    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
        if (t)cout << endl;
    }
    return 0;
}

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