Submission #578444

#	Time	Username	Problem	Language	Result	Execution time	Memory
578444		jeroenodb	Homecoming (BOI18_homecoming)	C++14	100 / 100	120 ms	16076 KiB

homecoming

#include "homecoming.h"
#include <algorithm>
#include <tuple>
using namespace std;
typedef long long ll;

const ll oo = -1e18;
long long solve(int N, int K, int *A, int *B) {
    int n = N,k = K;
    ll ans = 0;
    for(int rep=0;rep<2;++rep) {
        // rep==0: include a[0] certainly, so extra cost beyond the boundary does not have to be counted.
        // rep==1: doesn't matter if a[0] gets chosen or not.
        ll dp[2] = {};
        if(rep==0) dp[0] = oo;
        ll cost=0;
        for(int i=0;i<k;++i) cost+=B[i];
        dp[1] = A[0]-cost;
        
        for(int i=1;i<n;++i) {
            cost-=B[i-1];
            int extra=0;
            if(i+k-1<n) {
                extra = B[i+k-1];
            } else if(rep==1) {
                extra = B[i+k-1-n];
            }
            cost+=extra;
            tie(dp[0],dp[1]) = make_pair(max(dp[0],dp[1]), A[i]+ max(dp[0]-cost,dp[1]-extra));
        }
        ans = max({ans,dp[0],dp[1]});
    }
    return ans;
}

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