Submission #1023248

#	Time	Username	Problem	Language	Result	Execution time	Memory
1023248		daffuwu	Split the sequence (APIO14_sequence)	C++14	0 / 100	38 ms	82020 KiB

sequence

#include <bits/stdc++.h>
using namespace std;
#define fr first
#define sc second
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
 
int n, k, opt[100002][202], ps[100069];
vector<int> vc;
long long dp[100069][2];
 
bool mantap(long long c1, int m1, long long c2, int m2, long long c3, int m3)
{
    return (m2 != m3) && 1.0*(c1-c2)/(m2-m1)<1.0*(c2-c3)/(m3-m2);
}
 
long long calc(int id1, int id2, int c)
{
    long long res = dp[id1][c%2]+1ll*(ps[id2]-ps[id1])*ps[id1];
    if (res<0) res = -1e18;
    return res;
}
 
long long calc_c(int id, int c)
{
    return dp[id][c%2]-1ll*ps[id]*ps[id];
}
 
int main() 
{
    int i, j, c;
    scanf("%d%d", &n, &k);
    k++;
    for (i=1; i<=n; i++)
    {
        scanf("%d", ps+i);
        ps[i] += ps[i-1];
        dp[i][0] = -1e18;
    }
    for (c=1; c<=k; c++)
    {
        dp[0][c%2] = -1e18;
        for (i=1, j=0; i<=n; i++)
        {
            vc.push_back(i-1);
            for (; j+1<vc.size() && calc(vc[j], i, c-1)<calc(vc[j+1], i, c-1); j++);
            j = min(j, (int)vc.size()-1);
            opt[i][c] = vc[j];
            dp[i][c%2] = calc(vc[j], i, c-1);
            for (; vc.size()>=2 && !mantap(calc_c(vc.size()-2, c-1), ps[vc.size()-2], calc_c(vc.back(), c-1), ps[vc.back()], calc_c(i, c-1), ps[i]); vc.pop_back());
        }
    }
    printf("%lld\n", dp[n][k%2]);
    for (i=n, c=k; c>=2; i=opt[i][c], c--)
    {
        printf("%d ", opt[i][c]);
    }
    printf("\n");
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:45:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |             for (; j+1<vc.size() && calc(vc[j], i, c-1)<calc(vc[j+1], i, c-1); j++);
      |                    ~~~^~~~~~~~~~
sequence.cpp:31:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |     scanf("%d%d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~
sequence.cpp:35:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |         scanf("%d", ps+i);
      |         ~~~~~^~~~~~~~~~~~

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