Submission #767866

#	Time	Username	Problem	Language	Result	Execution time	Memory
767866		LucaIlie	Homecoming (BOI18_homecoming)	C++17	100 / 100	163 ms	116248 KiB

homecoming

#include <bits/stdc++.h>
#include "homecoming.h"

using namespace std;

const long long INF = 1e16;
const int MAX_N = 4e6 + 1;

deque <int> maxVal;
long long sumB[MAX_N], dp[MAX_N], val[MAX_N];

void add( int i ) {
    while ( !maxVal.empty() && val[i] > val[maxVal.back()] )
        maxVal.pop_back();
    maxVal.push_back( i );
}

void rem( int i ) {
    if ( !maxVal.empty() && maxVal.front() == i )
        maxVal.pop_front();
}

long long getVal( int i ) {
    if ( maxVal.empty() )
        return -INF;
    return dp[maxVal.front()] - (sumB[i + 1] - sumB[maxVal.front()]);
}

long long solve( int n, int k, int a[], int b[] ) {
    long long ans = 0;

    for ( int i = n; i <= n + k; i++ )
        sumB[i] = 0;
    for ( int i = n - 1; i >= 0; i-- )
        sumB[i] = sumB[i + 1] + b[i];

    for ( int take = 0; take <= 1; take++ ) {
        long long s = 0;
        for ( int i = 0; i <= k; i++ ) {
            dp[n + i] = -s * (1 - take);
            s += b[i];
        }

        maxVal.clear();
        for ( int i = n + k - 1; i >= n; i-- ) {
            val[i] = dp[i] + sumB[i];
            add( i );
        }


        long long maxA = dp[n + k];
        for ( int i = n - 1; i >= 0; i-- ) {
            dp[i] = -INF;
            if ( i >= k * take ) {
                dp[i] = max( getVal( i ), maxA );
                val[i] = dp[i] + sumB[i];
                add( i );
            }

            rem( i + k );
            maxA = max( maxA, dp[i + k] - (sumB[i + 1] - sumB[i + k]) );
            maxA = maxA - b[i] + a[i];
        }

        ans = max( ans, getVal( -1 ) );
        ans = max( ans, maxA );
    }

    return ans;
}

• Subtask 1: 13 / 13
• Subtask 2: 18 / 18
• Subtask 3: 31 / 31
• Subtask 4: 38 / 38