malls.cpp

#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

int main() {
    //  uncomment the following lines if you want to read/write from files
    // ifstream cin("input.txt");
    // ofstream cout("output.txt");

    long long N, K;
    cin >> N >> K;

    long long D[N];
    for (int i = 0; i < N; i++) {
        cin >> D[i];
    }

    // insert your code here
    sort(D, D+N);

    long long ans[2], temp, pos, d1, d2;   // ans[0] = pos, ans[1] = dist

    if (D[0] > K-D[N-1]){
        ans[0] = 0;
        ans[1] = D[0];
    } else {
        ans[0] = K;
        ans[1] = K-D[N-1];
    }

    for (int i=0; i<N-1; i++) {
        pos = (D[i] + D[i+1])/2;
        d1 = min (abs(D[i]-pos), abs(D[i+1]-pos));      // distanza a sinistra
        d2 = min (abs(D[i]-(pos+1)), abs(D[i+1]-(pos+1)));  // distanza a destra
        
        
        if (max(d1, d2) > ans[1]) {
            if (d1 > d2) {
                ans[0] = pos;
                ans[1] = d1; 
            } else {
                ans[0] = pos+1;
                ans[1] = d2;
            }
        }
    }

    cout << ans[0] << endl;  // change 42 with actual answer
    return 0;
}