Submission #61837

#	Time	Username	Problem	Language	Result	Execution time	Memory
61837		Benq	Homecoming (BOI18_homecoming)	C++11	31 / 100	1067 ms	24400 KiB

homecoming

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)

#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()

const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;

#include "homecoming.h"

ll dp[2000001][2], cumB[2000001];

ll get(int K, vi a, vi b) {
    int N = sz(a);
    dp[0][1] = -INF;
    FOR(i,1,N+1) cumB[i] = cumB[i-1]+b[i-1];
    FOR(i,1,N+1) {
        dp[i][0] = max(dp[i-1][0],dp[i-1][1]);
        if (i >= K) dp[i][1] = max(dp[i-K][0]+a[i-K]-(cumB[i]-cumB[i-K]),dp[i-1][1]+a[i-K]-b[i-1]);
        else dp[i][1] = -INF;
    }
    return max(dp[N][0],dp[N][1]);
}

long long int solve(int N, int K, int *A, int *B) {
    ll cur = 0;
    F0R(i,N) cur += A[i]-B[i];
    
    ll ans = max(0LL,cur);
    vi a, b;
    F0R(i,N) a.pb(A[i]), b.pb(B[i]);
    
    F0R(i,N) {
        ans = max(ans,get(K,a,b));
        rotate(a.begin(),a.begin()+1,a.end());
        rotate(b.begin(),b.begin()+1,b.end());
    }
    
    return ans;
}

/*int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    int A[3] = {40, 80, 100};
    int B[3] = {140, 0, 20};
    cout << solve(3, 2,A,B);
}*/

/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( ) 
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/

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