151 lines
2.8 KiB
C++
151 lines
2.8 KiB
C++
/* Problem URL: https://cses.fi/problemset/task/1628/ */
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#include <bits/stdc++.h>
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using namespace std;
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#define V vector
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#define rmin(a, b) a = min(a, b)
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#define rmax(a, b) a = max(a, b)
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#define rep(i, lim) for (int i = 0; i < (lim); i++)
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#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
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#define repv(i, v) for (auto &i : (v))
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#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
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#define sortv(v) sort(v.begin(), v.end())
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#define all(v) (v).begin(), (v).end()
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using vi = vector<int>;
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using vvi = vector<vi>;
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using vvvi = vector<vvi>;
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using vvvvi = vector<vvvi>;
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using ll = long long;
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using vl = vector<ll>;
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using vvl = vector<vl>;
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using vvvl = vector<vvl>;
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using vvvvl = vector<vvvl>;
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template<class v>
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auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
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os << vec[0];
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for (size_t i = 1; i < vec.size(); i++) {
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os << ' ' << vec[i];
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}
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os << '\n';
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<v> &vec)->istream& {
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for (auto &i : vec) {
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is >> i;
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}
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return is;
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}
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template<class v>
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auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
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for (auto &i : vec) {
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os << i[0];
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for (size_t j = 1; j < i.size(); j++) {
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os << ' ' << i[j];
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}
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os << '\n';
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}
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
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for (auto &i : vec) {
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for (auto &j : i) {
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is >> j;
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}
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}
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return is;
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}
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int main()
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{
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ios::sync_with_stdio(false);
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cin.tie(nullptr);
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int n;
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ll s;
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cin >> n >> s;
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vl fds(n);
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cin >> fds;
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int mid = n / 2;
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vl count;
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function<void(int, ll)> func1 = [&](int i, ll sum) {
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if (sum > s) {
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return;
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}
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if (i >= mid) {
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count.push_back(sum);
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return;
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}
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func1(i + 1, sum);
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func1(i + 1, sum + fds[i]);
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};
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ll ans = 0;
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vl sum;
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vl c;
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function<void(int, ll)> func2 = [&](int i, ll ss) {
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if (ss > s) {
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return;
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}
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if (i >= n - mid) {
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// ans += count[s - sum];
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auto itr = lower_bound(all(sum), s - ss);
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if (itr == sum.end() || *itr != s - ss) {
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return;
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}
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ans += c[itr - sum.begin()];
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return;
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}
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func2(i + 1, ss);
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func2(i + 1, ss + fds[i + mid]);
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};
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func1(0, 0);
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sortv(count);
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ll prev = count[0];
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int co = 1;
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nrep(i, 1, count.size()) {
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if (prev == count[i]) {
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co++;
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continue;
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}
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sum.push_back(prev);
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c.push_back(co);
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prev = count[i];
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co = 1;
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}
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sum.push_back(prev);
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c.push_back(co);
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func2(0, 0);
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cout << ans << '\n';
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}
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