input: Write a python function to calculate the maximum possible revenue from the items with given weights and values.
  assert knapsack([2, 1, 3], [4, 2, 3], 3) == 6
  assert knapsack([1, 2, 3], [6, 10, 12], 3) == 22
  assert knapsack([4, 5, 1], [1, 2, 3], 3) == 3
output: def knapsack(weights, values, max_weight):
      n = len(weights)
      dp = [[0 for _ in range(max_weight + 1)] for _ in range(n + 1)]
      
      for i in range(1, n + 1):
          for w in range(max_weight + 1):
              if weights[i-1] <= w:
                  dp[i][w] = max(dp[i-1][w], dp[i-1][w-weights[i-1]] + values[i-1])
              else:
                  dp[i][w] = dp[i-1][w]
      
      return dp[n][max_weight]