Submission #1156160

#	Time	Username	Problem	Language	Result	Execution time	Memory
1156160		nguyn	Watching (JOI13_watching)	C++20	100 / 100	662 ms	16152 KiB

watching

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

#define ll long long 
#define F first
#define S second
#define pb push_back 
#define pii pair<int,int>

const int N = 2e3 + 5;
const int inf = 2e9; 

int n, a[N], p, q; 
int f[N][N]; 

signed main(){
    ios_base::sync_with_stdio(false) ; 
    cin.tie(0) ; cout.tie(0) ; 
    if (fopen("INP.INP" ,"r")) {
        freopen("INP.INP" ,"r" , stdin) ;
        freopen("OUT.OUT" , "w" , stdout) ;
    }
    cin >> n >> p >> q;
    for (int i = 1; i <= n; i++) {
    	cin >> a[i]; 
    }
    sort(a + 1, a + 1 + n); 
    q = min(q, n); 
    int l = 1; 
    int r = 1e9; 
    int res = inf; 
    while(l <= r) {
    	int mid = (l + r) / 2; 
    	for (int i = 0; i <= n; i++) {
    		for (int j = 0; j <= q; j++) {
    			f[i][j] = -inf;
    		}
    	}
    	f[0][q] = p;
    	for (int i = 0; i < n; i++) {
    		for (int j = 0; j <= q; j++) {
    			if (f[i][j] == -inf) {
    				continue; 
    			}
    			if (j) {
    				int nxt = upper_bound(a + 1, a + 1 + n, a[i + 1] + 2 * mid - 1) - a - 1; 
    				f[nxt][j - 1] = max(f[nxt][j - 1], f[i][j]);   
    			}
    			int nxt = upper_bound(a + 1, a + 1 + n, a[i + 1] + mid - 1) - a - 1; 
    			f[nxt][j] = max(f[nxt][j], f[i][j] - 1); 
    		}
    	} 
    	bool ok = 0;
    	for (int i = 0; i <= q; i++) {
    		if (f[n][i] >= 0) ok = 1;
    	}
    	if (ok) {
    		res = mid; 
    		r = mid - 1; 
    	}
    	else {
    		l = mid + 1; 
    	}
    }
    cout << res; 
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:20:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |         freopen("INP.INP" ,"r" , stdin) ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:21:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         freopen("OUT.OUT" , "w" , stdout) ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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