const int maxn = 100 + 10;
int maxx[maxn], minn[maxn];
int a[maxn];int main()
{int T, n;while (scanf("%d", &T) != EOF){while (T--){scanf("%d", &n);for (int i = 0; i < n; i++)scanf("%d", &a[i]);sort(a, a+n);int ll = abs(a[0]-1e9);maxx[0] = max(a[1]-a[0], ll);for (int i = 1; i < n-1; i++)maxx[i] = max(a[i]-a[i-1], a[i+1]-a[i]);int rr = abs(1e9-a[n-1]);maxx[n-1] = max(a[n-1]-a[n-2], rr);double ans = 1e9;for (int i = 0; i < n; i++)ans = min((double)maxx[i], ans);printf("%.3f\n", ans);}}return 0;
}

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstdlib>
 4 #include <cstring>
 5 #include <algorithm>
 6 #include <cmath>
 7 #include <vector>
 8 using namespace std;
 9
10 #define eps 1e-9
11 #define pb push_back
12 const int maxn = 50 + 5;
13 vector<double> vd;
14 double a[maxn];
15 int n;
16
17 bool check(double gap)
18 {
19     double pre = a[0];
20     for (int i = 1; i < n; i++)
21     {
22         if (fabs(a[i]-pre) < eps)  // 没这句会wa
23             continue;
24         if (pre > a[i])
25             return false;
26         else if (pre + gap <= a[i])
27             pre = a[i];
28         else
29             pre = a[i] + gap; // 这一句意味深长啊，如果它更新后比下一个待检测的a[i]大，即：    if (pre > a[i])  就没有继续比较下去的必要
30     }
31     return true;
32 }
33
34 int main()
35 {
36     int T;
37     while (scanf("%d", &T) != EOF)
38     {
39         while (T--)
40         {
41             scanf("%d", &n);
42             for (int i = 0; i < n; i++)
43                 scanf("%lf", &a[i]);
44             sort(a, a+n);
45             for (int i = 1; i < n; i++)
46             {
47                 vd.pb(a[i]-a[i-1]);
48                 vd.pb((a[i]-a[i-1])/2);  // 别遗漏
49             }
50             double ans = 0;
51             for (int i = vd.size(); i >= 0; i--)
52             {
53                 if (check(vd[i]))
54                     ans = max(ans, vd[i]);
55             }
56             printf("%.3f\n", ans);
57         }
58     }
59     return 0;
60 }