description: Monocarp is playing yet another computer game. In this game, his character has to kill a dragon. The battle with the dragon lasts 100^{500} seconds, during which Monocarp attacks the dragon with a poisoned dagger. The i-th attack is performed at the beginning of the a_i-th second from the battle start. The dagger itself does not deal damage, but it applies a poison effect on the dragon, which deals 1 damage during each of the next k seconds (starting with the same second when the dragon was stabbed by the dagger). However, if the dragon has already been poisoned, then the dagger updates the poison effect (i.e. cancels the current poison effect and applies a new one).
  
  For example, suppose k = 4, and Monocarp stabs the dragon during the seconds 2, 4 and 10. Then the poison effect is applied at the start of the 2-nd second and deals 1 damage during the 2-nd and 3-rd seconds; then, at the beginning of the 4-th second, the poison effect is reapplied, so it deals exactly 1 damage during the seconds 4, 5, 6 and 7; then, during the 10-th second, the poison effect is applied again, and it deals 1 damage during the seconds 10, 11, 12 and 13. In total, the dragon receives 10 damage.
  
  Monocarp knows that the dragon has h hit points, and if he deals at least h damage to the dragon during the battle — he slays the dragon. Monocarp has not decided on the strength of the poison he will use during the battle, so he wants to find the minimum possible value of k (the number of seconds the poison effect lasts) that is enough to deal at least h damage to the dragon.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 1000) — the number of test cases.
  
  The first line of the test case contains two integers n and h (1 ≤ n ≤ 100; 1 ≤ h ≤ 10^{18}) — the number of Monocarp's attacks and the amount of damage that needs to be dealt.
  
  The second line contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 10^9; a_i < a_{i + 1}), where a_i is the second when the i-th attack is performed.
  
  Output
  
  For each test case, print a single integer — the minimum value of the parameter k, such that Monocarp will cause at least h damage to the dragon.
  
  Example
  
  Input
  
  
  4
  2 5
  1 5
  3 10
  2 4 10
  5 3
  1 2 4 5 7
  4 1000
  3 25 64 1337
  
  
  Output
  
  
  3
  4
  1
  470
  
  Note
  
  In the first example, for k=3, damage is dealt in seconds [1, 2, 3, 5, 6, 7].
  
  In the second example, for k=4, damage is dealt in seconds [2, 3, 4, 5, 6, 7, 10, 11, 12, 13].
  
  In the third example, for k=1, damage is dealt in seconds [1, 2, 4, 5, 7].
solution: import java.util.*;
  import java.io.*;
  
  public class C {
  
      public void prayGod() throws IOException {
          int t = nextInt();
  
          while (t-- > 0) {
              int n = nextInt();
              long h = nextLong();
              long[] a = nextLongArray(n);
  
              long low = 0, high = h, best = h;
              while (low <= high) {
                  long mid = low + (high - low) / 2;
                  long remain = h;
                  for (int i = 1; i < n; i++) {
                      remain -= Math.min(a[i] - a[i - 1], mid);
                      if (remain <= 0)
                          break;
                  }
                  remain -= mid;
                  if (remain <= 0) {
                      best = mid;
                      high = mid - 1;
                  } else {
                      low = mid + 1;
                  }
              }
              out.println(best);
  
          }
      }
  
      public long binpow(long a, long b) {
          if (b < 0)
              return 0;
          long ret = 1, curr = a;
          while (b > 0) {
              if (b % 2 == 1)
                  ret = (ret * curr) % mod;
              b /= 2;
              curr = (curr * curr) % mod;
          }
          return ret;
      }
  
      public void printVerdict(boolean verdict) {
          if (verdict)
              out.println(VERDICT_YES);
          else
              out.println(VERDICT_NO);
      }
  
      static final String VERDICT_YES = "YES";
      static final String VERDICT_NO = "NO";
      static final boolean RUN_TIMING = true;
      static final boolean AUTOFLUSH = false;
      static final boolean FILE_INPUT = false;
      static final boolean FILE_OUTPUT = false;
  
      static int iinf = 0x3f3f3f3f;
      static long inf = (long) 1e18 + 10;
      static int mod = (int) 1e9 + 7;
  
      static char[] inputBuffer = new char[1 << 20];
      static PushbackReader in = new PushbackReader(new BufferedReader(new InputStreamReader(System.in)), 1 << 20);
      static PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)), AUTOFLUSH);
  
      // int data-type
      public int nextInt() throws IOException {
          return Integer.parseInt(next());
      }
  
      public int[] nextIntArray(int n) throws IOException {
          int[] arr = new int[n];
          for (int i = 0; i < n; i++)
              arr[i] = nextInt();
          return arr;
      }
  
      public void sort(int[] a) {
          shuffle(a);
          Arrays.sort(a);
      }
  
      public static void printArray(int[] arr) {
          for (int i = 0; i < arr.length; i++)
              out.print(arr[i] + " ");
          out.println();
      }
  
      // long data-type
      public long nextLong() throws IOException {
          return Long.parseLong(next());
      }
  
      public long[] nextLongArray(int n) throws IOException {
          long[] arr = new long[n];
          for (int i = 0; i < n; i++)
              arr[i] = nextLong();
          return arr;
      }
  
      public static void printArray(long[] arr) {
          for (int i = 0; i < arr.length; i++)
              out.print(arr[i] + " ");
          out.println();
      }
  
      public void sort(long[] a) {
          shuffle(a);
          Arrays.sort(a);
      }
  
      // double data-type
      public double nextDouble() throws IOException {
          return Double.parseDouble(next());
      }
  
      public double[] nextDoubleArray(int n) throws IOException {
          double[] arr = new double[n];
          for (int i = 0; i < n; i++)
              arr[i] = nextDouble();
          return arr;
      }
  
      public static void printArray(double[] arr) {
          for (int i = 0; i < arr.length; i++)
              out.print(arr[i] + " ");
          out.println();
      }
  
      // Generic type
      public <T> void sort(T[] a) {
          shuffle(a);
          Arrays.sort(a);
      }
  
      public static <T> void printArray(T[] arr) {
          for (int i = 0; i < arr.length; i++)
              out.print(arr[i] + " ");
          out.println();
      }
  
      public String next() throws IOException {
          int len = 0;
          int c;
          do {
              c = in.read();
          } while (Character.isWhitespace(c) && c != -1);
          if (c == -1) {
              throw new NoSuchElementException("Reached EOF");
          }
          do {
              inputBuffer[len] = (char) c;
              len++;
              c = in.read();
          } while (!Character.isWhitespace(c) && c != -1);
          while (c != '\n' && Character.isWhitespace(c) && c != -1) {
              c = in.read();
          }
          if (c != -1 && c != '\n') {
              in.unread(c);
          }
          return new String(inputBuffer, 0, len);
      }
  
      public String nextLine() throws IOException {
          int len = 0;
          int c;
          while ((c = in.read()) != '\n' && c != -1) {
              if (c == '\r') {
                  continue;
              }
              inputBuffer[len] = (char) c;
              len++;
          }
          return new String(inputBuffer, 0, len);
      }
  
      public boolean hasNext() throws IOException {
          String line = nextLine();
          if (line.isEmpty()) {
              return false;
          }
          in.unread('\n');
          in.unread(line.toCharArray());
          return true;
      }
  
      public void shuffle(int[] arr) {
          int n = arr.length;
          for (int i = 0; i < n; i++) {
              int j = (int) (Math.random() * (n - i));
              int temp = arr[i];
              arr[i] = arr[j];
              arr[j] = temp;
          }
      }
  
      public void shuffle(long[] arr) {
          int n = arr.length;
          for (int i = 0; i < n; i++) {
              int j = (int) (Math.random() * (n - i));
              long temp = arr[i];
              arr[i] = arr[j];
              arr[j] = temp;
          }
      }
  
      public void shuffle(Object[] arr) {
          int n = arr.length;
          for (int i = 0; i < n; i++) {
              int j = (int) (Math.random() * (n - i));
              Object temp = arr[i];
              arr[i] = arr[j];
              arr[j] = temp;
          }
      }
  
      public static void main(String[] args) throws IOException {
          if (FILE_INPUT)
              in = new PushbackReader(new BufferedReader(new FileReader(new File("output.txt"))), 1 << 20);
          if (FILE_OUTPUT)
              out = new PrintWriter(new FileWriter(new File("output.txt")));
  
          long time = 0;
          time -= System.nanoTime();
          new C().prayGod();
          time += System.nanoTime();
  
          if (RUN_TIMING)
              System.err.printf("%.3f ms%n", time / 1000000.0);
  
          out.flush();
          in.close();
      }
  }