Submission #376859

#	Time	Username	Problem	Language	Result	Execution time	Memory
376859		2qbingxuan	Cake 3 (JOI19_cake3)	C++14	0 / 100	1 ms	364 KiB

cake3

#include <bits/stdc++.h>
#ifdef local
#define safe std::cerr<<__PRETTY_FUNCTION__<<" line "<<__LINE__<<" safe\n"
#define debug(a...) qqbx(#a, a)
template <typename ...T> void qqbx(const char *s, T ...a) {
    int cnt = sizeof...(T);
    ((std::cerr << "\033[1;32m(" << s << ") = (") , ... , (std::cerr << a << (--cnt ? ", " : "\033[0m)\n")));
}
#else
#define debug(...) ((void)0)
#define safe ((void)0)
#endif // local
#define all(v) begin(v),end(v)
 
using namespace std;
const int64_t INF = 1e18;
 
signed main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int n, m;
    cin >> n >> m;
    vector<pair<int64_t,int64_t>> cake(n);
    for (auto &[c, v]: cake) cin >> v >> c;
    sort(all(cake));

    auto calc = [&](int cost) -> pair<int64_t, int64_t> {
        pair<int64_t, int64_t> dp[3];
        dp[0] = {0, 0};
        dp[1] = dp[2] = {-INF, -INF};
        for (auto [c, v]: cake) {
            v -= cost;
            dp[2] = max(dp[2], make_pair(dp[1].first + v - c * 2, dp[1].second + 1));
            dp[1] = max(dp[1], make_pair(dp[1].first + v, dp[1].second + 1));
            dp[1] = max(dp[1], make_pair(dp[0].first + v, dp[0].second + 1));
            dp[0] = max(dp[0], make_pair(v + c * 2, (int64_t)1));
        }
        return dp[2];
    };

    int cost = 1 << 29;
    for (int s = 1 << 29; s; s>>=1) {
        if (calc(cost - s).second <= m) {
            cost -= s;
        }
    }
    auto [dp, k] = calc(cost);
    cout << dp + k * cost << '\n';

    /*
    vector<int64_t> dp(n, -1e18);
    vector<int64_t> ans(n+1, -1e18);

    for (int i = 0; i < n; i++) {
        auto [c, v] = cake[i];
        // ans = max(ans, dp[m-1] + v - c * 2);
        for (int j = 3; j <= n; j++)
            ans[j] = max(ans[j], dp[j-1] + v - c * 2);
        for (int j = n-2; j >= 1; j--) {
            dp[j+1] = max(dp[j+1], dp[j] + v);
        }
        dp[1] = max(dp[1], v + c * 2);
    }
    cerr << "==========\n";
    for (int j = 3; j <= n; j++)
        cerr << ans[j] - ans[j-1] << '\n';
    cout << ans[m] << '\n';
     */
}

Compilation message (stderr)

cake3.cpp: In function 'int main()':
cake3.cpp:23:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   23 |     for (auto &[c, v]: cake) cin >> v >> c;
      |                ^
cake3.cpp: In lambda function:
cake3.cpp:30:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   30 |         for (auto [c, v]: cake) {
      |                   ^
cake3.cpp: In function 'int main()':
cake3.cpp:46:10: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   46 |     auto [dp, k] = calc(cost);
      |          ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 19
• Subtask 3: 0 / 76