Submission #1116785

#	Time	Username	Problem	Language	Result	Execution time	Memory
1116785		Peter2017	Watching (JOI13_watching)	C++14	100 / 100	152 ms	16208 KiB

watching

#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pill pair<int,ll>
#define mem(a, b) memset(a, b, sizeof(a))
#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
#define name "test"

using namespace std;

const int N = 2e3 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;

template <typename T1, typename T2> bool maxi(T1 &a, T2 b){if (a < b){a = b; return 1;} return 0;}
template <typename T1, typename T2> bool mini(T1 &a, T2 b){if (a > b){a = b; return 1;} return 0;}

int n;
int P;
int Q;
int a[N];
int f[N][N];

void load(){
    cin.tie(0)->sync_with_stdio(0);
    if (fopen(name".inp", "r")){
        freopen(name".inp", "r", stdin);
        freopen(name".out", "w", stdout);
    }
}

void input(){
	cin >> n >> P >> Q;
	for (int i = 1; i <= n; i++)
		cin >> a[i];
}

bool check(int len){
	if (P + Q >= n) return 1;
	mem(f, 0x3f);
	int idA = 1;
	int idB = 1;
	f[0][0] = 0;
	for (int i = 1; i <= n; i++){
		while (a[i] - a[idA] + 1 > len) idA++;
		while (a[i] - a[idB] + 1 > 2 * len) idB++;
		for (int j = 0; j <= min(i, P); j++){
			mini(f[i][j + 1], f[idA - 1][j]);
			mini(f[i][j], f[idB - 1][j] + 1);
			if (j > 0) mini(f[i][j], f[i][j - 1]);
		}
	}
	return f[n][min(n, P)] <= Q;
}

void solve(){
	sort(a + 1, a + n + 1);
	int l = 1, r = 1e9, ans = r;
	while (l <= r){
		int m = (l + r) >> 1;
		if (check(m)){
			ans = m;
			r = m - 1;
		} else l = m + 1;
	}
	cout << ans;
}

int main(){
    load();
    input();
    solve();
}

Compilation message (stderr)

watching.cpp: In function 'void load()':
watching.cpp:31:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |         freopen(name".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:32:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |         freopen(name".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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