Submission #250451

#	Time	Username	Problem	Language	Result	Execution time	Memory
250451		combi1k1	Collecting Stamps 3 (JOI20_ho_t3)	C++14	100 / 100	93 ms	66424 KiB

ho_t3

#include<bits/stdc++.h>

using namespace std;

#define ll  long long
#define ld  double

#define sz(x)   (int)x.size()
#define all(x)  x.begin(),x.end()

#define pb  emplace_back
#define X   first
#define Y   second

const int   N  = 205;

int x[N];
int t[N];
ll  f[N][N][N][2];

int main()  {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int n;  cin >> n;
    int L;  cin >> L;

    for(int i = 1 ; i <= n ; ++i)   cin >> x[i];
    for(int i = 1 ; i <= n ; ++i)   cin >> t[i];

    for(int i = 1 ; i <= n ; ++i)
        f[0][0][i][0] = 2e18,
        f[0][0][i][1] = 2e18;
    
    x[n + 1] = L;

    for(int i = 0 ; i <= n ; ++i)
    for(int j = 0 ; j <= n ; ++j)   {
        if (i < 1 && j < 1) continue;
        if (i + j > n)      break;
        
        for(int k = 0 ; k <= n ; ++k)   {
            ll& res1 = f[i][j][k][0];   res1 = 2e18;
            ll& res2 = f[i][j][k][1];   res2 = 2e18;

            if (i)
                res1 = min(res1,f[i - 1][j][k][0] + x[n - i + 2] - x[n - i + 1]),
                res1 = min(res1,f[i - 1][j][k][1] + x[j]     + L - x[n - i + 1]);
            if (j)
                res2 = min(res2,f[i][j - 1][k][0] + x[j] + L - x[n - i + 1]),
                res2 = min(res2,f[i][j - 1][k][1] + x[j] - x[j - 1]);

            if (k == 0) continue;

            ll  nxt;

            if (i)  {
                if ((nxt = f[i - 1][j][k - 1][0] + x[n - i + 2] - x[n - i + 1]) <= t[n - i + 1])    res1 = min(res1,nxt);
                if ((nxt = f[i - 1][j][k - 1][1] + x[j]     + L - x[n - i + 1]) <= t[n - i + 1])    res1 = min(res1,nxt);
            }
            if (j)  {
                if ((nxt = f[i][j - 1][k - 1][0] + x[j] + L - x[n - i + 1]) <= t[j])    res2 = min(res2,nxt);
                if ((nxt = f[i][j - 1][k - 1][1] + x[j] - x[j - 1])         <= t[j])    res2 = min(res2,nxt);
            }
        }
    }
    int ans = 0;

    for(int i = 0 ; i <= n ; ++i)
    for(int k = 0 ; k <= n ; ++k)   {
        if (f[i][n - i][k][0] < 2e18)   ans = max(ans,k);
        if (f[i][n - i][k][1] < 2e18)   ans = max(ans,k);
    }
    cout << ans << endl; 
}

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