Submission #332963

#	Time	Username	Problem	Language	Result	Execution time	Memory
332963		limabeans	Collecting Stamps 3 (JOI20_ho_t3)	C++17	100 / 100	363 ms	135412 KiB

ho_t3

#include <bits/stdc++.h>
using namespace std;

template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl





using ll = long long;

const ll inf = 1e18;
const int maxn = 205;



ll n,l;
ll x[maxn], t[maxn];


ll dp[maxn][maxn][2][maxn]; // left end, right end, which end?, taken


// 0, 1,2,...,n
// n+1

ll f(int l, int r, int p, int taken) {
    if (l<0 || l>n+1) return inf;
    if (r<0 || r>n+1) return inf;
    if (p<0) return inf;
    ll &res = dp[l][r][p][taken];
    if (~res) return res;
    res = inf;

    // don't take
    if (p==0 && l>0) {
	res = min(res, f(l-1,r,0,taken)+(x[l]-x[l-1]));
	res = min(res, f(l-1,r,1,taken)+(x[n+1]-x[r])+x[l]);
    }
    if (p==1 && r<n+1) {
	res = min(res, f(l,r+1,1,taken)+(x[r+1]-x[r]));
	res = min(res, f(l,r+1,0,taken)+x[l]+(x[n+1]-x[r]));
    }

    // take
    if (taken>0) {
	ll tmp = -1;
	if (p==0 && l>0) {
	    tmp = f(l-1,r,0,taken-1)+(x[l]-x[l-1]);
	    if (tmp<=t[l]) {
		res = min(res, tmp);
	    }
	    tmp = f(l-1,r,1,taken-1)+(x[n+1]-x[r])+x[l];
	    if (tmp<=t[l]) {
		res = min(res, tmp);
	    }
	}
	
	if (p==1 && r<n+1) {
	    tmp = f(l,r+1,1,taken-1)+(x[r+1]-x[r]);
	    if (tmp<=t[r]) {
		res = min(res, tmp);
	    }
	    tmp = f(l,r+1,0,taken-1)+(x[n+1]-x[r])+x[l];
	    if (tmp<=t[r]) {
		res = min(res, tmp);
	    }
	}
    }
    
    return res;
}

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

    cin>>n>>l;
    for (int i=1; i<=n; i++) {
	cin>>x[i];
    }
    x[0] = 0;
    x[n+1] = l;
    
    for (int i=1; i<=n; i++) {
	cin>>t[i];
    }

    int ans = 0;
    memset(dp,-1,sizeof(dp));
    dp[0][n+1][0][0] = 0;
    dp[0][n+1][1][0] = 0;

    for (int x=0; x<n+1; x++) {
	for (int taken=1; taken<=n; taken++) {
	    if (f(x,x+1,0,taken)<inf) ans = max(ans, taken);
	    if (f(x,x+1,1,taken)<inf) ans = max(ans, taken);
	}
    }


    cout<<ans<<endl;    
    return 0;
}

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