Submission #1269841

#	Time	Username	Problem	Language	Result	Execution time	Memory
1269841		yanb	Homecoming (BOI18_homecoming)	C++20	0 / 100	285 ms	203936 KiB

homecoming

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

using namespace std;

#define int long long

int solves(int n, int k, signed *A, signed *B, int shift) {
    vector<int> a(2 * n), b(2 * n);
    for (int i = 0; i < n; i++) {
        a[i] = a[i + n] = A[(i + shift) % n];
        b[i] = b[i + n] = B[(i + shift) % n];
    }

    vector<int> pa(2 * n + 1), pb(2 * n + 1);
    for (int i = 0; i < 2 * n; i++) {
        pa[i + 1] = pa[i] + a[i];
        pb[i + 1] = pb[i] + b[i];
    }

    vector<int> dp(n + 1, -1e17), dpm(2 * n + 1, -1e17);
    dp[0] = -pb[k - 1];
    dpm[k] = dp[0];
    int ans = dp[0];
    for (int i = 0; i < n - k; i++) {
        dp[i + 1] = max({dp[i] + a[i] - b[i + k - 1], dpm[i] + a[i] - pb[i + k] + pb[i]});
        dpm[i + k + 1] = max(dpm[i + k], dp[i + 1]);
    }

    vector<int> maxsuff(n + 1);
    for (int i = n - 1; i >= 0; i--) {
        maxsuff[i] = max(maxsuff[i], pa[n] - pa[i] - pb[n] + pb[i]);
    }

    for (int i = 0; i < n - k; i++) {
        ans = max(ans, dp[i + 1] + maxsuff[i + k]);
    }

    return ans;
}

int solvet(int n, int k, signed *A, signed *B, int shift) {
    vector<int> a(2 * n), b(2 * n);
    for (int i = 0; i < n; i++) {
        a[i] = a[i + n] = A[(i + shift) % n];
        b[i] = b[i + n] = B[(i + shift) % n];
    }

    vector<int> pa(2 * n + 1), pb(2 * n + 1);
    for (int i = 0; i < 2 * n; i++) {
        pa[i + 1] = pa[i] + a[i];
        pb[i + 1] = pb[i] + b[i];
    }

    vector<int> dp(n + 1, -1e17), dpm(2 * n + 1);
    int ans = dp[0];
    for (int i = 0; i < n; i++) {
        dp[i + 1] = max({dp[i] + a[i] - b[i + k - 1], dpm[i] + a[i] - pb[i + k] + pb[i]});
        dpm[i + k + 1] = max(dpm[i + k], dp[i + 1]);
    }

    for (int i = 0; i < n; i++) {
        ans = max(ans, dp[i + 1]);
    }

    return ans;
}


int solve(signed n, signed k, signed *A, signed *B) {
    int ans = max(0ll, accumulate(A, A + n, 0ll) - accumulate(B, B + n, 0ll));
    ans = max(ans, solves(n, k, A, B, 0));
    ans = max(ans, solvet(n, k, A, B, 0));
    return ans;
}

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