Submission #839291

#	Time	Username	Problem	Language	Result	Execution time	Memory
839291		hafo	Watching (JOI13_watching)	C++14	100 / 100	159 ms	16068 KiB

watching

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pa pair<int, int>
#define pall pair<ll, int>
#define fi first
#define se second
#define TASK "test"
#define Size(x) (int) x.size()
#define all(x) x.begin(), x.end()
using namespace std;

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

const int MOD = 1e9 + 7;
const int LOG = 20;
const int maxn = 2e3 + 7;
const ll oo = 1e9 + 69;

int n, p, q, a[maxn], dp[maxn][maxn];

bool check(int w) {
    for(int i = 1; i <= n; i++) {
        int l1 = lower_bound(a + 1, a + 1 + n, a[i] - w + 1) - a;
        int l2 = lower_bound(a + 1, a + 1 + n, a[i] - 2 * w + 1) - a;
        for(int j = 0; j <= p; j++) {
            dp[i][j] = oo;
            if(j > 0) mini(dp[i][j], dp[l1 - 1][j - 1]);
            mini(dp[i][j], dp[l2 - 1][j] + 1);
            if(i == n && dp[i][j] <= q) return 1;
        }
    }
    return 0;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    //freopen(TASK".inp", "r", stdin);
    //freopen(TASK".out", "w", stdout);

    cin>>n>>p>>q;
    mini(p, n);
    mini(q, n);
    for(int i = 1; i <= n; i++) cin>>a[i];
    sort(a + 1, a + 1 + n);
    
    int l = 1, r = 1e9, mid, res;
    while(l <= r) {
        mid = l + r >> 1;
        if(check(mid)) {
            res = mid;
            r = mid - 1;
        } else l = mid + 1;
    }
    cout<<res;
    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:53:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   53 |         mid = l + r >> 1;
      |               ~~^~~
watching.cpp:59:11: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
   59 |     cout<<res;
      |           ^~~

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