description: In Berland, n different types of banknotes are used. Banknotes of the i-th type have denomination 10^{a_i} burles (burles are the currency used in Berland); the denomination of banknotes of the first type is exactly 1.
  
  Let's denote f(s) as the minimum number of banknotes required to represent exactly s burles. For example, if the denominations of banknotes used in Berland are 1, 10 and 100, then f(59) = 14: 9 banknotes with denomination of 1 burle and 5 banknotes with denomination of 10 burles can be used to represent exactly 9 ⋅ 1 + 5 ⋅ 10 = 59 burles, and there's no way to do it with fewer banknotes.
  
  For a given integer k, find the minimum positive number of burles s that cannot be represented with k or fewer banknotes (that is, f(s) > k).
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — number of test cases.
  
  The first line of each test case contains two integers n and k (1 ≤ n ≤ 10; 1 ≤ k ≤ 10^9).
  
  The next line contains n integers a_1, a_2, ..., a_n (0 = a_1 < a_2 < ... < a_n ≤ 9).
  
  Output
  
  For each test case, print one integer — the minimum positive number of burles s that cannot be represented with k or fewer banknotes.
  
  Example
  
  Input
  
  
  4
  3 13
  0 1 2
  2 777
  0 4
  3 255
  0 1 3
  10 1000000000
  0 1 2 3 4 5 6 7 8 9
  
  
  Output
  
  
  59
  778
  148999
  999999920999999999
solution: import bisect
  import heapq
  import math
  import collections
  import sys
  import copy
  from functools import reduce
  import decimal
  from io import BytesIO, IOBase
  import os
  import itertools
  import functools
  from types import GeneratorType
  
  #
  # sys.setrecursionlimit(10 ** 9)
  decimal.getcontext().rounding = decimal.ROUND_HALF_UP
  
  graphDict = collections.defaultdict
  
  queue = collections.deque
  
  
  ################## pypy deep recursion handling ##############
  # Author = @pajenegod
  def bootstrap(f, stack=[]):
      def wrappedfunc(*args, **kwargs):
          to = f(*args, **kwargs)
          if stack:
              return to
          else:
              while True:
                  if type(to) is GeneratorType:
                      stack.append(to)
                      to = next(to)
                  else:
                      stack.pop()
                      if not stack:
                          return to
                      to = stack[-1].send(to)
  
      return wrappedfunc
  
  
  ################## Graphs ###################
  class Graphs:
      def __init__(self):
          self.graph = graphDict(set)
  
      def add_edge(self, u, v):
          self.graph[u].add(v)
          self.graph[v].add(u)
  
      def dfs_utility(self, nodes, visited_nodes, colors, parity, level):
          global count
          if nodes == 1:
              colors[nodes] = -1
          else:
              if len(self.graph[nodes]) == 1 and parity % 2 == 0:
                  if q == 1:
                      colors[nodes] = 1
                  else:
                      colors[nodes] = -1
                      count += 1
              else:
                  if parity % 2 == 0:
                      colors[nodes] = -1
                  else:
                      colors[nodes] = 1
          visited_nodes.add(nodes)
          for neighbour in self.graph[nodes]:
              new_level = level + 1
              if neighbour not in visited_nodes:
                  self.dfs_utility(neighbour, visited_nodes, colors, level - 1, new_level)
  
      def dfs(self, node):
          Visited = set()
          color = collections.defaultdict()
          self.dfs_utility(node, Visited, color, 0, 0)
          return color
  
      def bfs(self, node, f_node):
          count = float("inf")
          visited = set()
          level = 0
          if node not in visited:
              queue.append([node, level])
              visited.add(node)
          flag = 0
          while queue:
              parent = queue.popleft()
              if parent[0] == f_node:
                  flag = 1
                  count = min(count, parent[1])
              level = parent[1] + 1
              for item in self.graph[parent[0]]:
                  if item not in visited:
                      queue.append([item, level])
                      visited.add(item)
          return count if flag else -1
          return False
  
  
  ################### Tree Implementaion ##############
  class Tree:
      def __init__(self, data):
          self.data = data
          self.left = None
          self.right = None
  
  
  def inorder(node, lis):
      if node:
          inorder(node.left, lis)
          lis.append(node.data)
          inorder(node.right, lis)
      return lis
  
  
  def leaf_node_sum(root):
      if root is None:
          return 0
      if root.left is None and root.right is None:
          return root.data
      return leaf_node_sum(root.left) + leaf_node_sum(root.right)
  
  
  def hight(root):
      if root is None:
          return -1
      if root.left is None and root.right is None:
          return 0
      return max(hight(root.left), hight(root.right)) + 1
  
  
  ################## Union Find #######################
  class UF:
      """An implementation of union find data structure.
      It uses weighted quick union by rank with path compression.
      """
  
      def __init__(self, N):
          """Initialize an empty union find object with N items.
  
          Args:
              N: Number of items in the union find object.
          """
  
          self._id = list(range(N))
          self._count = N
          self._rank = [0] * N
  
      def find(self, p):
          """Find the set identifier for the item p."""
  
          id = self._id
          while p != id[p]:
              p = id[p]  # Path compression using halving.
          return p
  
      def count(self):
          """Return the number of items."""
  
          return self._count
  
      def connected(self, p, q):
          """Check if the items p and q are on the same set or not."""
  
          return self.find(p) == self.find(q)
  
      def union(self, p, q):
          """Combine sets containing p and q into a single set."""
  
          id = self._id
          rank = self._rank
  
          i = self.find(p)
          j = self.find(q)
          if i == j:
              return
  
          self._count -= 1
          if rank[i] < rank[j]:
              id[i] = j
          elif rank[i] > rank[j]:
              id[j] = i
          else:
              id[j] = i
              rank[i] += 1
  
      def add_roads(self):
          return set(self._id)
  
      def __str__(self):
          """String representation of the union find object."""
          return " ".join([str(x) for x in self._id])
  
      def __repr__(self):
          """Representation of the union find object."""
          return "UF(" + str(self) + ")"
  
  
  #################################################
  
  def rounding(n):
      return int(decimal.Decimal(f'{n}').to_integral_value())
  
  
  def factors(n):
      return set(reduce(list.__add__,
                        ([i, n // i] for i in range(1, int(n ** 0.5) + 1) if n % i == 0)))
  
  
  def p_sum(array):
      return list(itertools.accumulate(array))
  
  
  def base_change(nn, bb):
      if nn == 0:
          return [0]
      digits = []
      while nn:
          digits.append(int(nn % bb))
          nn //= bb
      return digits[::-1]
  
  
  def diophantine(a: int, b: int, c: int):
      d, x, y = extended_gcd(a, b)
      r = c // d
      return r * x, r * y
  
  
  @bootstrap
  def extended_gcd(a: int, b: int):
      if b == 0:
          d, x, y = a, 1, 0
      else:
          (d, p, q) = yield extended_gcd(b, a % b)
          x = q
          y = p - q * (a // b)
  
      yield d, x, y
  
  
  ######################################################################################
  
  '''
  Knowledge and awareness are vague, and perhaps better called illusions.
  Everyone lives within their own subjective interpretation.
                                                              ~Uchiha Itachi
  '''
  
  ################################ <fast I/O> ###########################################
  BUFSIZE = 8192
  
  
  class FastIO(IOBase):
      newlines = 0
  
      def __init__(self, file):
          self._fd = file.fileno()
          self.buffer = BytesIO()
          self.writable = "x" in file.mode or "r" not in file.mode
          self.write = self.buffer.write if self.writable else None
  
      def read(self):
          while True:
              b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
              if not b:
                  break
              ptr = self.buffer.tell()
              self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
          self.newlines = 0
          return self.buffer.read()
  
      def readline(self, **kwargs):
          while self.newlines == 0:
              b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
              self.newlines = b.count(b"\n") + (not b)
              ptr = self.buffer.tell()
              self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
          self.newlines -= 1
          return self.buffer.readline()
  
      def flush(self):
          if self.writable:
              os.write(self._fd, self.buffer.getvalue())
              self.buffer.truncate(0), self.buffer.seek(0)
  
  
  class IOWrapper(IOBase):
      def __init__(self, file):
          self.buffer = FastIO(file)
          self.flush = self.buffer.flush
          self.writable = self.buffer.writable
          self.write = lambda s: self.buffer.write(s.encode("ascii"))
          self.read = lambda: self.buffer.read().decode("ascii")
          self.readline = lambda: self.buffer.readline().decode("ascii")
  
  
  sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
  
  
  #############################################<I/O Region >##############################################
  
  
  def inp():
      return sys.stdin.readline().strip()
  
  
  def map_inp(v_type):
      return map(v_type, inp().split())
  
  
  def list_inp(v_type):
      return list(map_inp(v_type))
  
  
  ######################################## Solution ####################################
  
  for _ in range(int(inp())):
      n, k = map_inp(int)
      arr = map_inp(int)
      arr = [10 ** item for item in arr]
      ans = 0
      for i in range(n - 1):
          a, b = divmod(arr[i + 1] - 1, arr[i])
          if a + b > k:
              if k < 10:
                  ans = arr[i] + k
                  break
              else:
                  k += 1
                  for item in range(0, n - 1):
                      if k < 0:
                          break
                      ans += min(k, (arr[item + 1] - 1) // arr[item]) * arr[item]
                      k -= min(k, (arr[item + 1] - 1) // arr[item])
                  if k > 0:
                      ans += k * arr[n - 1]
                  break
      if ans == 0:
          k += 1
          for item in range(0, n - 1):
              if k < 0:
                  break
              ans += min(k, (arr[item + 1] - 1) // arr[item]) * arr[item]
              k -= min(k, (arr[item + 1] - 1) // arr[item])
          if k > 0:
              ans += k * arr[n - 1]
      print(ans)
  