Submission #707428

#	Time	Username	Problem	Language	Result	Execution time	Memory
707428		DennisTran	Split the sequence (APIO14_sequence)	C++17	0 / 100	11 ms	4436 KiB

sequence

#include <bits/stdc++.h>
#define FOR(i, x, y) for (int i = x; i < y; i++)
typedef long long ll;
using namespace std;

int n, k;
int where[201][100001];
ll pref[100001]{0}, dp[2][100001], q[100001], l = 1, r = 1;

bool case1(int x, int y, int i) {
	return (dp[0][y] - dp[0][x] >= (pref[y] - pref[x]) * (pref[n] - pref[i]));
}

bool case2(int x, int y, int i) {
	return ((dp[0][y] - dp[0][x]) * (pref[i] - pref[y]) <=
	        (dp[0][i] - dp[0][y]) * (pref[y] - pref[x]));
}
#define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".ans", "w", stdout); }

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	file("TASK");
	cin >> n >> k;
	FOR(i, 1, n + 1) {
		int x;
		cin >> x;
		pref[i] = pref[i - 1] + x;
	}

	fill(dp[0], dp[0] + n + 1, 0);
	FOR(i, 1, k + 1) {
		q[r++] = 0;
		FOR(j, 1, n + 1) {
			while (r - l > 1 && case1(q[l], q[l + 1], j)) l++;

			ll x = q[l];
			dp[1][j] = dp[0][x] + (pref[j] - pref[x]) * (pref[n] - pref[j]);
			where[i][j] = x;

			while (r - l > 1 && case2(q[r - 2], q[r - 1], j)) r--;
			q[r++] = j;
		}
		l = r = 1;
		FOR(j, 1, n + 1) dp[0][j] = dp[1][j];
	}

	ll mx = -1;
	int indx = -1;
	FOR(i, 1, n + 1) {
		if (dp[0][i] > mx) mx = dp[0][i], indx = i;
	}
	cout << mx << '\n';
	return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:49:6: warning: variable 'indx' set but not used [-Wunused-but-set-variable]
   49 |  int indx = -1;
      |      ^~~~
sequence.cpp:18:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".ans", "w", stdout); }
      |                                                   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:23:2: note: in expansion of macro 'file'
   23 |  file("TASK");
      |  ^~~~
sequence.cpp:18:91: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".ans", "w", stdout); }
      |                                                                                    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:23:2: note: in expansion of macro 'file'
   23 |  file("TASK");
      |  ^~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29