Submission #861524

#	Time	Username	Problem	Language	Result	Execution time	Memory
861524		maks007	Homecoming (BOI18_homecoming)	C++14	100 / 100	128 ms	95944 KiB

homecoming

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

using namespace std;

#define intl long long

intl solve(int n, int k, int *A, int *B) {
	vector <intl> a, b, pref(n);
	function <intl(intl)> get=[&](intl l) {
		intl r = l + k - 1;
		if(r < n) return pref[r] - (l?pref[l-1]:0LL);
		r %= n;
		return pref[r] + (pref[n-1] - (l?pref[l-1]:0LL));
	};
	for(int i = 0; i < n; i ++) a.push_back(A[i]);
	for(int i = 0; i < n; i ++) b.push_back(B[i]);
	for(int i = 0; i < n; i ++) {
		if(i) pref[i] = pref[i-1];
		pref[i] += b[i];
	}
	intl dp[n][2];
	for(int i = 0; i < n; i ++) {
		for(int j = 0; j < n; j ++) dp[i][j] = -1e18;
	}
	dp[0][1] = a[0] - pref[k-1];
	for(int i = 1; i < n; i ++) {
		dp[i][0] = max(dp[i-1][1], dp[i-1][0]);
		dp[i][1] = max(dp[i-1][1] + a[i] - (i + k - 1 < n ? b[i+k-1] : 0LL),
				       dp[i-1][0] + a[i] - (pref[min(n-1,i+k-1)] - (i ? pref[i-1] : 0LL)));
	}
	intl ans = max(dp[n-1][1], dp[n-1][0]);
	for(int i = 0; i < n; i ++) {
		for(int j = 0; j < n; j ++) dp[i][j] = -1e18;
	}
	dp[0][0] = 0;
	for(int i = 1; i < n; i ++) {
		dp[i][0] = max(dp[i-1][1], dp[i-1][0]);
		dp[i][1] = max(dp[i-1][1] + a[i] - b[(i + k - 1) % n], dp[i-1][0] + a[i] - get(i));
	}
	ans = max({ans, dp[n-1][0], dp[n-1][1]});
	return ans;
} 

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