Submission #700266

#	Time	Username	Problem	Language	Result	Execution time	Memory
700266		nguyentunglam	Split the sequence (APIO14_sequence)	C++17	100 / 100	879 ms	81472 KiB

sequence

#include<bits/stdc++.h>
#define fi first
#define se second
#define endl "\n"
#define ii pair<int, int>
using namespace std;
const int N = 1e5 + 2;
long long f[N], g[N], s[N];
int used[210][N];
struct line {
    long long m, c;
    int trace;
    long long eval(long long x) { return m * x + c; }
    long long calcx (line l) { return (c - l.c) / (l.m - m); }
};
int main() {
    #define task ""
    cin.tie(0) -> sync_with_stdio(0);
    if (fopen ("task.inp", "r")) {
        freopen ("task.inp", "r", stdin);
        freopen ("task.out", "w", stdout);
    }
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    int n, k; cin >> n >> k;
    ++k;
    for(int i = 1; i <= n; i++) {
        cin >> s[i];
        s[i] += s[i - 1];
    }
    for(int j = 1; j <= k; j++) {
        deque<line> dq;
        dq.push_back({0, 0, 0});
        for(int i = 1; i <= n; i++) {
            while (dq.size() >= 2 && dq.back().eval(s[i]) <= dq[dq.size() - 2].eval(s[i])) dq.pop_back();
            f[i] = dq.back().eval(s[i]) + s[i] * s[n] - s[i] * s[i];
            used[j][i] = dq.back().trace;
            line cur = {s[i], g[i] - s[i] * s[n], i};
            if (!dq.empty() && dq.front().m == cur.m) {
                if (cur.c >= dq.front().c) dq.pop_front();
                else continue;
            }
            while (dq.size() >= 2 && cur.calcx(dq[0]) <= dq[0].calcx(dq[1])) dq.pop_front();
            dq.push_front(cur);
        }
        for(int i = 1; i <= n; i++) g[i] = f[i];
    }
    cout << g[n] << endl;
    int cur = n, j = k;
    for(int j = k; j >= 2; j--) {
        cur = used[j][cur];
        cout << cur << " ";
    }
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:51:18: warning: unused variable 'j' [-Wunused-variable]
   51 |     int cur = n, j = k;
      |                  ^
sequence.cpp:20:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |         freopen ("task.inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:21:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         freopen ("task.out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:24:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:25:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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