Submission #886690

#	Time	Username	Problem	Language	Result	Execution time	Memory
886690		AgentPengin	Watching (JOI13_watching)	C++14	100 / 100	332 ms	31860 KiB

watching

/**
 *    author:  AgentPengin ( Độc cô cầu bại )
 *    created: 23.12.2022 10:08:02
 *    too lazy to update time
**/
#include<bits/stdc++.h>

#define EL '\n'
#define fi first
#define se second
#define NAME "TASK"
#define ll long long
#define lcm(a,b) (a/gcd(a,b))*b
#define db(val) "["#val" = " << (val) << "] "
#define bend(v) (v).begin(),(v).end()
#define sz(v) (int)(v).size()
#define ex exit(0)

using namespace std;

const ll mod = 1e9 + 7;
const int inf = 0x1FFFFFFF;
const int MAXN = 2005;

int n,P,Q,a[MAXN];
pair<int,int> dp[MAXN][MAXN];

inline void maximize(pair<int,int>& u,const pair<int,int> v) {
	if (v.fi < u.fi) u = v;
	else if (v.fi == u.fi && v.se > u.se) u = v;
}

bool check(int mid) {
	// dp[i] = {P,Q} -> uu tien su dung P truoc Q sau
	// dp[i][j] -> the first i-th, use j type 1, fi type 2, go second
	for (int i = 1;i <= n;i++) {
		for (int j = 0;j <= P;j++) dp[i][j] = make_pair(inf,0);
	}
	dp[1][0] = make_pair(1,2 * mid - 1);
	dp[1][1] = make_pair(0,mid - 1);
	
	for (int i = 1;i < n;i++) {
		for (int j = 0;j <= P;j++) {
			if (a[i + 1] - a[i] <= dp[i][j].se) {
				maximize(dp[i + 1][j],make_pair(dp[i][j].fi,dp[i][j].se - (a[i + 1] - a[i])));
			}
			if (j < P)
			maximize(dp[i + 1][j + 1],make_pair(dp[i][j].fi,mid - 1));
			
			maximize(dp[i + 1][j],make_pair(dp[i][j].fi + 1,2 * mid - 1));
		}
	}
	
	for (int j = 0;j <= P;j++) {
		if (dp[n][j].fi <= Q) return true;
	}
	return false;	
}

signed main() {
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    if (ifstream(NAME".inp")) {
        freopen(NAME".inp","r",stdin);
        freopen(NAME".out","w",stdout);
    }
    cin >> n >> P >> Q;
    if (P + Q >= n) return cout << 1,0;
    for (int i = 1;i <= n;i++) cin >> a[i];
    sort(a + 1,a + n + 1);
	int l = 1,r = 1e9,ans = 1e9;
	while(l <= r) {
		int mid = l + r >> 1;
		if (check(mid)) {
			ans = mid;
			r = mid - 1;
		} else {
			l = mid + 1;
		}
	}
    
    cout << ans;
    cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
    return 0;
}
// agent pengin wants to take apio (with anya-san)

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:72:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   72 |   int mid = l + r >> 1;
      |             ~~^~~
watching.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen(NAME".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
watching.cpp:64:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   64 |         freopen(NAME".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50