Submission #1097208

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097208		crafticat	Feast (NOI19_feast)	C++17	100 / 100	477 ms	5816 KiB

feast

#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#include "bits/stdc++.h"

using namespace std;
template<typename T>
using V = vector<T>;
using ll = long long;
using pi = pair<ll, int>;
#define ckmax(a,b) a = max(a,b)

inline std::pair<long long, int> operator-(const std::pair<long long, int>& p1, const std::pair<long long, int>& p2) {
    return {p1.first - p2.first, p1.second - p2.second};
}

pi solve(V<ll>&arr, ll k, ll p) {
    V<pi> dp(2,{-1e18,0});
    dp[0] = {0,0};
    pi pa = make_pair(p,-1);

    for (ll i = 1; i <= arr.size(); ++i) {
        auto newDp = dp;

        newDp[1] = {-1e18,0};
        newDp[0] = {0,0};
        for (ll l = 0; l < 2; ++l) {
            ckmax(newDp[l], max(max(dp[1], dp[0]) - pa, dp[1]));
        }

        ckmax(newDp[0], dp[0]);
        newDp[1].first += arr[i - 1];
        dp = newDp;
    }

    return max(dp[0], dp[1]);
}

int main() {
    ll n, k; cin >> n >> k;

    V<ll> arr(n);
    for (ll i = 0; i < n; ++i) {
        cin >> arr[i];
    }


    ll l = 0, r = 1e18;
    int iter = 0;
    while (r > l) {
        ll mid = l + (r - l + 1) / 2;
        if (solve(arr, k, mid).second >= k)
            l = mid;
        else
            r = mid - 1;
    }

    cout << solve(arr,k,l).first + l * k << "\n";
}

Compilation message (stderr)

feast.cpp:3: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    3 | #pragma GCC optimization ("O3")
      | 
feast.cpp:4: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    4 | #pragma GCC optimization ("unroll-loops")
      | 
feast.cpp: In function 'pi solve(V<long long int>&, ll, ll)':
feast.cpp:23:22: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int, std::allocator<long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |     for (ll i = 1; i <= arr.size(); ++i) {
      |                    ~~^~~~~~~~~~~~~
feast.cpp: In function 'int main()':
feast.cpp:50:9: warning: unused variable 'iter' [-Wunused-variable]
   50 |     int iter = 0;
      |         ^~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29