Submission #1016692

#	Time	Username	Problem	Language	Result	Execution time	Memory
1016692		GrindMachine	Homecoming (BOI18_homecoming)	C++17	31 / 100	387 ms	262144 KiB

homecoming

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

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

#include "homecoming.h"

ll solve(int n, int k, int *A, int *B){
    vector<ll> a(n), b(n);
    rep(i,n) a[i] = A[i], b[i] = B[i];
    ll initial = 0;
    rep(i,n) initial += a[i]-b[i];
    ll ans = 0;

    auto aa = a, bb = b;
    rep(i,n) aa.pb(a[i]), bb.pb(b[i]);
    vector<ll> pa(2*n), pb(2*n);
    rep(i,2*n){
        pa[i] = aa[i]+(i?pa[i-1]:0);
        pb[i] = bb[i]+(i?pb[i-1]:0);
    }

    vector<ll> smx(2*n+5,-inf2);
    rev(i,2*n-1,0){
        smx[i] = max(smx[i+1],pb[i]-pa[i]);
    }

    vector<pll> cands;
    rep(i,n){
        ll sum = 0;
        ll d = 0;
        ll mx = -inf2;
        ll val = pa[i]-pb[i+k-1]+smx[i+k];
        amax(mx,val);            

        // for(int j = i+1; j != i; j = (j+1)%n){
        //     sum -= a[j];
        //     d++;
        //     if(d >= k) sum += b[j];
        //     amax(mx,sum);
        // }

        cands.pb({mx,i});
    }

    sort(rall(cands));
    ll iter = 0;

    for(auto [val,s] : cands){
        iter++;
        if(iter > 5) break;

        rotate(a.begin(),a.begin()+s,a.end());
        rotate(b.begin(),b.begin()+s,b.end());

        vector<ll> p(n);
        rep(i,n){
            p[i] = a[i]+(i?p[i-1]:0);
        }

        ll dp[n][2];
        memset(dp,-0x3f,sizeof dp);
        dp[0][0] = 0;

        rep(i,n-1){
            // j = 0
            {
                // pass next guy
                amax(dp[i+1][0],dp[i][0]);

                // start a failing sequence
                if(i+k < n){
                    amax(dp[i+k][1],dp[i][0]+b[i+k]-p[i+k]+p[i]);
                }
            }

            // j = 1
            {
                // pass next guy
                amax(dp[i+1][0],dp[i][1]);

                // fail next guy
                amax(dp[i+1][1],dp[i][1]+b[i+1]-a[i+1]);
            }
        }

        ll mx = 0;
        rep(j,2) amax(mx,dp[n-1][j]);
        amax(ans,mx);

        rotate(a.begin(),a.begin()+n-s,a.end());
        rotate(b.begin(),b.begin()+n-s,b.end());
    }

    ans += initial;
    amax(ans,0ll);
    return ans;
}

Compilation message (stderr)

homecoming.cpp: In function 'll solve(int, int, int*, int*)':
homecoming.cpp:84:12: warning: unused variable 'sum' [-Wunused-variable]
   84 |         ll sum = 0;
      |            ^~~
homecoming.cpp:85:12: warning: unused variable 'd' [-Wunused-variable]
   85 |         ll d = 0;
      |            ^

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