Submission #44563

#	Time	Username	Problem	Language	Result	Execution time	Memory
44563		chpipis	Watching (JOI13_watching)	C++11	100 / 100	323 ms	16920 KiB

watching

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pf push_front
#define iter(v, i) for (__typeof__((v).begin()) i = (v).begin(); i != (v).end(); i++)
#define fast_io_without_cstdio ios_base::sync_with_stdio(false), cin.tie(NULL)
#define all(v) (v).begin(), (v).end()
#define rep(i, s, e) for (int i = s; i < e; i++)

// START for segment tree
#define params int p, int L, int R
#define housekeep int mid = (L + R) >> 1, left = p << 1, right = left | 1
// END

#ifdef __linux__
#define gc getchar_unlocked
#define pc putchar_unlocked
#else
#define gc getchar
#define pc putchar
#endif

#if __cplusplus <= 199711L
template<class BidirIt>
BidirIt prev(BidirIt it, typename iterator_traits<BidirIt>::difference_type n = 1) {
    advance(it, -n);
    return it;
}

template<class ForwardIt>
ForwardIt next(ForwardIt it, typename iterator_traits<ForwardIt>::difference_type n = 1) {
    advance(it, n);
    return it;
}
#endif

typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long double ldouble;

const double EPS = 1e-9;
const double PI = 3.141592653589793238462;

template<typename T>
inline T sq(T a) { return a * a; }

//#ifdef LOCAL_MACHINE
//#endif

const int MAXN = 2005;

int n, p, q;
int ev[MAXN], dp[MAXN][MAXN];
int prep[MAXN], preq[MAXN];

bool can(int w) {
    int ptr = 0;
    for (int i = 1; i <= n; i++) {
        while (ptr < i && ev[i] - w + 1 > ev[ptr])
            ptr++;
        prep[i] = ptr - 1;
    }
    ptr = 0;
    for (int i = 1; i <= n; i++) {
        while (ptr < i && ev[i] - 2 * w + 1 > ev[ptr])
            ptr++;
        preq[i] = ptr - 1;
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j <= q; j++) {
            dp[i][j] = dp[prep[i]][j] + 1;
            if (j > 0)
                dp[i][j] = min(dp[i][j], dp[preq[i]][j - 1]);
        }
    }
    //printf("can(%d) ? %d\n", w, (int)(dp[n][q] <= p));
    return dp[n][q] <= p;
}

int main() {
    //freopen("", "r", stdin);
    //freopen("", "w", stdout);
    scanf("%d %d %d", &n, &p, &q);
    ev[0] = -2e9;
    for (int i = 1; i <= n; i++)
        scanf("%d", &ev[i]);
    sort(ev + 1, ev + n + 1);
    if (p + q >= n) {
        puts("1");
    } else {
        int lo = 1, hi = 1e9;
        while (lo < hi) {
            int mid = (lo + hi) >> 1;
            if (can(mid)) {
                hi = mid;
            } else {
                lo = mid + 1;
            }
        }
        printf("%d\n", hi);
    }
    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:90:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d %d", &n, &p, &q);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:93:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &ev[i]);
         ~~~~~^~~~~~~~~~~~~~

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