Submission #553958

#	Time	Username	Problem	Language	Result	Execution time	Memory
553958		AA_Surely	Watching (JOI13_watching)	C++14	0 / 100	1074 ms	15984 KiB

watching

#include <bits/stdc++.h>

#define FOR(i,x,n) 	for(int i=x; i<n; i++)
#define F0R(i,n) 	FOR(i,0,n)
#define ROF(i,x,n) 	for(int i=n-1; i>=x; i--)
#define R0F(i,n) 	ROF(i,0,n)

#define WTF 		cout << "WTF" << endl

#define IOS 		ios::sync_with_stdio(false); cin.tie(0)
#define F 			first
#define S	 		second
#define pb 			push_back

#define ALL(x) 		x.begin(), x.end()
#define RALL(x) 	x.rbegin(), x.rend()

using namespace std;
typedef long long 		LL;

typedef pair<int, int> 	PII;
typedef pair<LL, LL> 	PLL;

typedef vector<int> 	VI;
typedef vector<LL> 		VLL;
typedef vector<PII> 	VPII;
typedef vector<PLL> 	VPLL;

const int N = 2000 + 7;
const int ALPHA = 27;
const int INF = 1e9 + 7;
const int MOD = 1e9 + 7;
const int LOG = 22;

int n, s, b;
int ns[N], dp[N][N];
// dp[i][j] = until i'th place, having j small cameras.

inline bool check(int w) {
    FOR(i, 1, n + 1) F0R(j, n + 1) {
        int pl = lower_bound(ns + 1, ns + n + 1, ns[i] - 2 * w) - ns;
        //cout << "when updating " << i << ' ' << j << " using " << pl - 1 << ' ' << j << endl;

        dp[i][j] = dp[pl - 1][j] + 1;
        if (j) {
            pl = lower_bound(ns + 1, ns + n + 1, ns[i] - w) - ns;
            dp[i][j] = min(dp[i][j], dp[pl - 1][j - 1]);
            //cout << "but when updating " << i << ' ' << j << " using " << pl - 1 << ' ' << j - 1 << endl;
        }
    }
    
    //cout << "check(" << w << ") = " << dp[n][min(n, s)] << endl;
    //FOR(i, 1, n + 1) F0R(j, n + 1) cout << dp[i][j] << " \n"[j == n];
    
    return (dp[n][min(n, s)] <= b);
}

int main() {
    IOS;
    
    cin >> n >> s >> b;
    FOR(i, 1, n + 1) cin >> ns[i];
    ns[0] = -INF;

    sort(ns + 1, ns + n + 1);
    int l = 1, r = INF;

    //cout << check(4) << endl;
    while(l < r) {
        int mid = (l + r) >> 1;
        if (check(mid)) r = mid;
        else l = mid + 1;
    }

    cout << l + 1;
}

• Subtask 1: 0 / 50
• Subtask 2: 0 / 50