Submission #1087058

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087058		Icelast	Collecting Stamps 3 (JOI20_ho_t3)	C++17	100 / 100	128 ms	130900 KiB

ho_t3

#include <iostream>
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll maxn = 205, INF = 4e18+9;
struct stamp{
    ll x, t;
};
ll dp[maxn][maxn][maxn][2];
void solve(){
    int n, L;
    cin >> n >> L;
    vector<stamp> a(n+2);
    for(int i = 1; i <= n; i++){
        cin >> a[i].x;
    }
    for(int i = 1; i <= n; i++){
        cin >> a[i].t;
    }
    a[0] = {0, INF};
    a[n+1] = {0, INF};
    auto C = [&](int i, int j) -> ll{
        if(a[i].x < a[j].x) swap(i, j);
        return min(a[i].x - a[j].x, L+(a[j].x-a[i].x));
    };
    auto chmin = [&](ll &a, ll b) -> void{
        a = min(a, b);
    };
    for(int i = 0; i <= n; i++){
        for(int j = 0; j <= n; j++){
            for(int k = 0; k <= n; k++){
                dp[i][j][k][0] = dp[i][j][k][1] = INF;
            }
        }
    }
    dp[1][n][0][0] = dp[1][n][0][1] = 0;
    for(int len = n-1; len >= 0; len--){
        for(int i = 1; i <= n-len+1; i++){
            int j = i+len-1;
            for(int k = 0; k <= n; k++){
                if(i > 1) chmin(dp[i][j][k][0], dp[i-1][j][k][0] + C(i-1, i-1-1));
                if(j < n) chmin(dp[i][j][k][1], dp[i][j+1][k][1] + C(j+1, j+1+1));

                if(i > 1) chmin(dp[i][j][k][0], dp[i-1][j][k][1] + C(j+1, i-1));
                if(j < n) chmin(dp[i][j][k][1], dp[i][j+1][k][0] + C(i-1, j+1));

                if(k == 0) continue;

                if(i > 1 && dp[i-1][j][k-1][0] + C(i-1, i-1-1) <= a[i-1].t) chmin(dp[i][j][k][0], dp[i-1][j][k-1][0] + C(i-1, i-1-1));
                if(j < n && dp[i][j+1][k-1][1] + C(j+1, j+1+1) <= a[j+1].t) chmin(dp[i][j][k][1], dp[i][j+1][k-1][1] + C(j+1, j+1+1));


                if(i > 1 && dp[i-1][j][k-1][1] + C(j+1, i-1) <= a[i-1].t) chmin(dp[i][j][k][0], dp[i-1][j][k-1][1] + C(j+1, i-1));
                if(j < n && dp[i][j+1][k-1][0] + C(i-1, j+1) <= a[j+1].t) chmin(dp[i][j][k][1], dp[i][j+1][k-1][0] + C(i-1, j+1));
            }
        }
    }
    int ans = 0;
    for(int i = 0; i <= n; i++){
        for(int j = 0; j <= n; j++){
            for(int k = n; k >= 0; k--){
                if(min(dp[i][j][k][0], dp[i][j][k][1]) < INF){
                    ans = max(ans, k);
                }
            }
        }
    }
    cout << ans;
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    solve();
}

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