Submission #1290632

#	Time	Username	Problem	Language	Result	Execution time	Memory
1290632		Bui_Quoc_Cuong	Feast (NOI19_feast)	C++20	100 / 100	115 ms	21560 KiB

feast

#include <bits/stdc++.h>
#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (a); i >= (b); i--)
#define REP(i, n) for (int i = 0; i < (n); i++)
#define ll long long
#define ALL(x) (x).begin(), (x).end()
#define TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define fi first
#define se second
using namespace std;

const int N = 3e5 + 5;

int n, k;
int a[N];
pair <ll, int> dp[N][4];

pair <ll, int> calc(ll lamda) {
	dp[1][0] = {0, 0};
	dp[1][1] = {a[1] - lamda, 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][0].fi + a[i] - lamda, dp[i - 1][0].se + 1), 
					   make_pair(dp[i - 1][1].fi + a[i], dp[i - 1][1].se));
	}
	return max(dp[n][0], dp[n][1]);
}

void solve() {
	cin >> n >> k;
	for(int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	ll sum = 0;
	FOR(i, 1, n) if(a[i] > 0) sum+= a[i];
	ll l = 1, r = sum, ans = 0;
	while(l <= r) {
		int mid = (l + r) / 2;
		if(calc(mid).se >= k) ans = mid, l = mid + 1;
		else r = mid - 1;
	}
	cout << max(1ll * 0, 1ll * ans * k + calc(ans).fi);
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    file("feast");

    solve();

    cerr << "Time used: " << TIME << " s.\n";
    return (0 ^ 0);
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:9:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:50:5: note: in expansion of macro 'file'
   50 |     file("feast");
      |     ^~~~
feast.cpp:9:91: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:50:5: note: in expansion of macro 'file'
   50 |     file("feast");
      |     ^~~~

• 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