Aggressive cows

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cstring>
 4 #include<cmath>
 5 #include<queue>
 6 #include<stack>
 7 #include<string>
 8 #include<algorithm>
 9 #include<map>
10 #include<sstream>
11 #include<set>
12 #define debug(x) cout << "[" << #x <<": " << (x) <<"]"<< endl
13 #define CLE(a,b) memset(a,b,sizeof(a))
14 #define MEC(a,b) memcpy(a,b,sizeof(a))
15 #define ll long long
16 #define inff 0x7fffffff
17 //const int dx[9] = { 0,1,-1,0,0,-1,-1,1,1 };
18 //const int dy[9] = { 0,0,0,-1,1,-1,1,-1,1 };
19 //const int dx[9] = { 0,0,1,-1 };
20 //const int dy[9] = { 1,-1,0,0 };
21 //struct {
22 
23 //};
24 const int inf = 1e9 + 5;
25 ll book[100005];
26 int c, n;
27 int judge(int d)
28 {
29     int cur, lef = 0;
30     for (int i = 1;i < c;i++)
31     {
32         cur = lef + 1;
33         while (cur < n && book[cur] - book[lef] < d)
34         {
35             cur++;
36         }
37         if (cur == n)
38             return 0;
39         lef = cur;
40     }
41     return 1;
42 }
43 using namespace std;
44 int main()
45 {
46     cin >> n >> c;
47     for (int i = 0;i < n;i++)
48     {
49         cin >> book[i];
50     }
51     sort(book, book + n);
52     int l = 0, r = inf;
53     int ans = 0;
54     while (r >= l)
55     {
56         int mid = (l + r) >> 1;
57         if (judge(mid))
58         {
59             ans = mid;
60             l = mid + 1;
61         }
62         else r = mid - 1;
63     }
64     cout << ans << endl;
65     return 0;
66 }