PZDC

#include <iomanip>
#include <iostream>
#include <cmath>
#define INT_MAX 2000000000

using namespace std;

int binary_search(int *a, int n, int x) {
    auto L = -1;
    auto R = n;
    while (R - L > 1) {
        auto M = (L + R) / 2;
        if (a[M] < x)
            L = M;
        else
            R = M;
    }
    return R;
}

int main() {
    // n - stoila, k - cows
    int n, k;
    std::cin >> n >> k;
    int *count = new int[n] {0};
    int *a = new int[n];
    for (int i = 0; i < n; i++)
        cin >> a[i];
    if (k <= 2) {
        cout << a[n - 1] - a[0] << endl;
        system("pause");
        exit(0);
    }
    k -= 2;
    count[0]++;
    count[n - 1]++;
    int l = 0, r = n - 1;
    int dist, min = INT_MAX;
    while (k != 0) {
        int m = (n % 2 == 0 ? n / 2 : (n + 1) / 2);
        if (abs(a[r] - a[m]) < abs(a[l] - a[m])) {
            dist = abs(a[l] - a[m]);
            if (dist < min)
                min = dist;
            r = m;
            count[r]++;
        }
        else {
            dist = abs(a[r] - a[m]);
            if (dist < min)
                min = dist;
            l = m;
            count[l]++;
        }
        k--;
    }
    int meet = 0, z;
    for (int i = 0; i < n - 1; i++) {
        if (count[i]) {
            if (meet == 0)
                meet = i;
            else {
                z = a[i] - a[meet];
                if (z < min)
                    min = z;
            }
        }
    }
    cout << min << endl;
    system("pause");
    return 0;
}