Submission #612551

#	Time	Username	Problem	Language	Result	Execution time	Memory
612551		amunduzbaev	Homecoming (BOI18_homecoming)	C++17	100 / 100	155 ms	78584 KiB

homecoming

#ifndef EVAL
#include "homecoming.h"
#endif
#include "bits/stdc++.h"
using namespace std;

typedef long long ll;

const int N = 2e6 + 5;
ll dp[N][2], pa[N], pb[N];

ll solve(int n, int k, int a[], int b[]){
	for(int i=0;i<n;i++){
		pa[i] = a[i];
		if(i) pa[i] += pa[i-1];
		pb[i] = b[i];
		if(i) pb[i] += pb[i-1];
	}
	
	for(int i=0;i<n;i++) memset(dp[i], 254, sizeof dp[i]);
	dp[0][1] = a[0] - pb[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] : 0), 
					dp[i-1][0] + a[i] - (pb[min(i + k - 1, n - 1)] - pb[i - 1]));
	}
	
	ll res = max(dp[n - 1][0], dp[n - 1][1]);
	for(int i=0;i<n;i++) memset(dp[i], 254, sizeof dp[i]);
	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] - (pb[min(i + k - 1, n - 1)] - pb[i - 1] + (i + k > n ? pb[i + k - 1 - n] : 0)));
	}
	
	res = max({res, dp[n - 1][0], dp[n - 1][1]});
	return res;
}

/*

1
3 2
40 80 100
140 0 20

*/

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