Submission #795394

#	Time	Username	Problem	Language	Result	Execution time	Memory
795394		Theo830	Collecting Stamps 3 (JOI20_ho_t3)	C++17	100 / 100	93 ms	135232 KiB

ho_t3

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e18+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ll,ii>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll n;
    cin>>n;
    ll l;
    cin>>l;
    ll x[n+2];
    x[0] = 0;
    f(i,1,n+1){
        cin>>x[i];
    }
    x[n+1] = l;
    ll t[n+2];
    t[0] = t[n+1] = -1;
    f(i,1,n+1){
        cin>>t[i];
    }
    ll dp[205][205][205][2];
    f(i,0,n+5){
        f(j,0,n+5){
            f(k,0,n+5){
                f(u,0,2){
                    dp[i][j][k][u] = INF;
                }
            }
        }
    }
    ll ans = 0;
    f(i,0,n+1){
        f(j,0,n+1){
            if(i + j <= n){
                f(k,0,n+1){
                    if(k == 0){
                        dp[i][j][k][0] = dp[i][j][k][1] = l - x[n+1-i] + x[j];
                    }
                    dp[i][j+1][k][0] = min({dp[i][j+1][k][0],dp[i][j][k][0] + x[j+1] - x[j],dp[i][j][k][1] + l - x[n+1-i] + x[j+1]});
                    dp[i+1][j][k][1] = min({dp[i+1][j][k][1],dp[i][j][k][1] + x[n+1-i] - x[n-i],dp[i][j][k][0] + x[j] + l - x[n-i]});
                    if(min(dp[i][j][k][0] + x[j+1] - x[j],dp[i][j][k][1] + l - x[n+1-i] + x[j+1]) <= t[j+1]){
                        dp[i][j+1][k+1][0] = min({dp[i][j+1][k+1][0],dp[i][j][k][0] + x[j+1] - x[j],dp[i][j][k][1] + l - x[n+1-i] + x[j+1]});
                    }
                    if(min(dp[i][j][k][1] + x[n+1-i] - x[n-i],dp[i][j][k][0] + x[j] + l - x[n-i]) <= t[n-i]){
                        dp[i+1][j][k+1][1] = min({dp[i+1][j][k+1][1],dp[i][j][k][1] + x[n+1-i] - x[n-i],dp[i][j][k][0] + x[j] + l - x[n-i]});
                    }
                    f(u,0,2){
                        if(dp[i][j][k][u] < INF){
                            ans = max(ans,k);
                        }
                    }
                }
            }
        }
    }
    cout<<ans<<"\n";
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 75 / 75