Submission #1123474

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123474		btninh	Feast (NOI19_feast)	C++17	100 / 100	139 ms	11000 KiB

feast

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define fi first
#define se second
#define TASK "A"
const int N = 3e5 + 5;

int n, k, a[N];
pair<ll,ll> dp[N][2];

pair<ll,ll> Calc(ll lmd){

    dp[1][0] = {0, 0};
    dp[1][1] = {a[1] - lmd, 1};
    for(int i = 2; i <= n; ++i){
        dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
        dp[i][1] = max(make_pair(dp[i - 1][1].fi + a[i], dp[i - 1][1].se),
                       make_pair(dp[i - 1][0].fi + a[i] - lmd, dp[i - 1][0].se + 1));
    }
    return max(dp[n][0], dp[n][1]);
}

signed main()
{
    if(fopen(TASK".inp", "r")){
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> n >> k;
    for(int i = 1; i <= n; ++i) cin >> a[i];
    ll l = 0, r = 1e18;
    while (l < r)
    {
        ll mid = (l + r + 1) >> 1LL;
        if (Calc(mid).se >= k) l = mid;
        else r = mid - 1;
    }
    cout << Calc(l).fi + l * k;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:28:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:29:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• 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