Submission #158407

#	Time	Username	Problem	Language	Result	Execution time	Memory
158407		mhy908	Split the sequence (APIO14_sequence)	C++14	100 / 100	608 ms	87088 KiB

sequence

#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define llinf 8987654321987654321
using namespace std;
typedef long long LL;
typedef pair<int, int> pii;
typedef pair<LL, LL> pll;
int n, k;
LL arr[100010], sum[100010], dp[2][100010];
int pass[210][100010];
struct LinearFunc{
    LL a, b;
    int c;
    long double s;
    LinearFunc(): LinearFunc(1, 0, 0){}
    LinearFunc(LL a1, LL b1, int c1): a(a1), b(b1), s(0), c(c1){}
}f[100010];
long double cross(LinearFunc &f, LinearFunc &g){
    return (long double)(g.b-f.b)/(long double)(f.a-g.a);
}
void print(int num, int x){
    if(num<=1)return;
    print(num-1, pass[num][x]);
    printf("%d ", pass[num][x]);
}
int main()
{
    scanf("%d %d", &n, &k);
    for(int i=1; i<=n; i++)scanf("%lld", &arr[i]), sum[i]=sum[i-1]+arr[i];
    for(int i=1; i<=n; i++)dp[0][i]=llinf;
    for(int j=1; j<=k+1; j++){
        int top=0, fpos=0;
        for(int i=j; i<=n; i++){
            LinearFunc g(-2*sum[i-1], dp[(j+1)%2][i-1]+sum[i-1]*sum[i-1], i-1);
            bool flag=true;
            while(top>0){
                if(f[top-1].a!=g.a){
                    g.s=cross(f[top-1], g);
                    if(f[top-1].s<g.s)break;
                    if(--top==fpos)fpos--;
                }
                else{
                    if(f[top-1].b<=g.b){
                        flag=false;
                        break;
                    }
                    if(--top==fpos)fpos--;
                }
            }
            if(flag)f[top++]=g;
            LL x=sum[i];
            while(fpos+1<top&&f[fpos+1].s<x)fpos++;
            dp[j%2][i]=f[fpos].a*x+f[fpos].b+sum[i]*sum[i];
            pass[j][i]=f[fpos].c;
        }
    }
    printf("%lld\n", (sum[n]*sum[n]-dp[(k+1)%2][n])/2);
    print(k+1, n);
}
/*
5 1
0 1 0 0 1
*/

Compilation message (stderr)

sequence.cpp: In constructor 'LinearFunc::LinearFunc(LL, LL, int)':
sequence.cpp:16:17: warning: 'LinearFunc::s' will be initialized after [-Wreorder]
     long double s;
                 ^
sequence.cpp:15:9: warning:   'int LinearFunc::c' [-Wreorder]
     int c;
         ^
sequence.cpp:18:5: warning:   when initialized here [-Wreorder]
     LinearFunc(LL a1, LL b1, int c1): a(a1), b(b1), s(0), c(c1){}
     ^~~~~~~~~~
sequence.cpp: In function 'int main()':
sequence.cpp:30:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &k);
     ~~~~~^~~~~~~~~~~~~~~~~
sequence.cpp:31:50: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1; i<=n; i++)scanf("%lld", &arr[i]), sum[i]=sum[i-1]+arr[i];
                            ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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