Submission #283526

#	Time	Username	Problem	Language	Result	Execution time	Memory
283526		zecookiez	Watching (JOI13_watching)	C++14	100 / 100	797 ms	31992 KiB

watching

#include <bits/stdc++.h>
using namespace std;
template<class C>constexpr int len(const C&c){return int(c.size());}
const int MAXN = 2003;
int N, P, Q;
long long W, arr[MAXN], dp[MAXN][MAXN];
int helper(int pos, int left, long long loc){
    if(pos == N) return 0;
    //cout << pos << " " << left << " " << loc << endl;
    if(loc > arr[pos]) return helper(pos + 1, left, loc);
    if(dp[pos][left] != -1) return dp[pos][left];
    int ans = helper(pos + 1, left, arr[pos] + W + W) + 1;
    if(left > 0) ans = min(ans, helper(pos + 1, left - 1, arr[pos] + W));
    return dp[pos][left] = ans;
}
bool check(long long w){
    memset(dp, -1, sizeof(dp)); W = w;
    return helper(0, P, 0) <= Q;
}
int main(){
    cin.sync_with_stdio(0); cin.tie(0); cout.tie(0);
    //freopen("haybales.in", "r", stdin);
    //freopen("haybales.out", "w", stdout);
    // Bsearch on answer
    // Check:
    //     DP[i][j] = Minimum large cameras for first i and j small cameras
    cin >> N >> P >> Q;
    if(P + Q >= N){ // thanks JOI
        cout << "1\n"; return 0;
    }
    for(int i = 0; i < N; ++i) cin >> arr[i];
    sort(arr, arr + N);
    long long mid, left = -1, right = 1e9 + 1;
    while(right - left > 1){
        mid = left + (right - left) / 2LL;
        if(check(mid)) right = mid;
        else left = mid;
    }
    cout << right << '\n';
    return 0;
}

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