Submission #98830

#	Time	Username	Problem	Language	Result	Execution time	Memory
98830		MvC	Homecoming (BOI18_homecoming)	C++11	13 / 100	103 ms	8312 KiB

homecoming

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

using namespace std;

void subtaskAsserts(int N, int K, int a[], int b[]) {
    assert(N <= 500);
}

typedef long long int lint;

const int NMAX   = 2000000;
const int VALMAX = 1000000000;

void asserts(int N, int K, int a[], int b[]) {
    assert(1 <= K && K <= N && N <= NMAX);
    for (int i = 0; i < N; ++ i) {
        assert(0 <= a[i] && a[i] <= VALMAX);
        assert(0 <= b[i] && b[i] <= VALMAX);
    }
}

int A[2 * NMAX + 5], B[2 * NMAX + 5];
lint dp[2 * NMAX + 5];

lint solve(int N, int K, int a[], int b[]) {
    asserts(N, K, a, b), subtaskAsserts(N, K, a, b);

    // Copy and double a, b for internal use
    for (int i = 0; i < N; ++ i) {
        A[i] = a[i], A[N + i] = a[i];
        B[i] = b[i], B[N + i] = b[i];
    }

    // Try to take all textbooks
    lint ans = 0;
    for (int i = 0; i < N; ++ i)
        ans += A[i] - B[i];

    // Fix a textbook we'll NOT take
    for (int i = 0; i < N; ++ i) {
        dp[i + N] = 0;
        for (int j = i + N - 1; j >= i + 1; -- j) {
            dp[j] = dp[j + 1];
            lint cost = 0;
            for (int k = j; k <= j + K - 2; ++ k)
                cost -= B[k];
            for (int k = j + K - 1; k < i + N; ++ k) {
                cost += A[k - K + 1] - B[k];
                dp[j] = max(dp[j], cost + dp[k + 1]);
            }
        }
        ans = max(ans, dp[i + 1]);
    }

    return ans;
}

• Subtask 1: 13 / 13
• Subtask 2: 0 / 18
• Subtask 3: 0 / 31
• Subtask 4: 0 / 38