Submission #255869

#	Time	Username	Problem	Language	Result	Execution time	Memory
255869		imeimi2000	Homecoming (BOI18_homecoming)	C++17	100 / 100	208 ms	118124 KiB

homecoming

#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <unordered_map>
#include <functional>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include "homecoming.h"
 
using namespace std;
typedef long long llong;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<llong, llong> pll;
 
const llong inf = 1e18;
int n, k;
int a[2000001];
int b[2000001];
llong bs[2000001];
 
llong getSum(int i, int j) {
    if (j <= n) return bs[j] - bs[i - 1];
    return bs[j - n] + bs[n] - bs[i - 1];
}
 
void setMax(llong &x, llong y) {
    if (x < y) x = y;
}
 
llong dp[2000001][2];
llong solve(int N, int K, int A[], int B[]) {
    n = N;
    k = K;
    for (int i = 1; i <= n; ++i) {
        a[i] = A[i - 1];
        b[i] = B[i - 1];
        bs[i] = bs[i - 1] + b[i];
    }
    
    for (int i = 0; i <= n; ++i) {
        dp[i][0] = dp[i][1] = -inf;
    }
    
    llong ans1 = dp[1][0] = 0;
    for (int i = 2; i <= n; ++i) {
        if (k < i) setMax(dp[i][0], dp[i - k][1]);
        setMax(dp[i][0], dp[i - 1][0]);
        
        setMax(dp[i][1], dp[i - 1][1] + a[i] - b[(i + k - 2) % n + 1]);
        setMax(dp[i][1], dp[i - 1][0] + a[i] - getSum(i, i + k - 1));
        ans1 = max({ ans1, dp[i][0], dp[i][1] });
    }
    
    for (int i = 0; i <= n; ++i) {
        dp[i][0] = dp[i][1] = -inf;
    }
    
    llong ans2 = dp[1][1] = a[1] - getSum(1, k);
    for (int i = 2; i <= n; ++i) {
        if (k < i) setMax(dp[i][0], dp[i - k][1]);
        setMax(dp[i][0], dp[i - 1][0]);
        
        int x = i + k - 1;
        setMax(dp[i][1], dp[i - 1][1] + a[i] - (x > n ? 0 : b[x]));
        setMax(dp[i][1], dp[i - 1][0] + a[i] - getSum(i, min(i + k - 1, n)));
        ans2 = max({ ans2, dp[i][0], dp[i][1] });
    }
    return max(ans1, ans2);
}

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