input: Write a function to solve a knapsack problem using dynamic programming. The function should return the maximum value that can be obtained given a list of items with their values and weights, and a capacity limit for the knapsack. If the list of items is empty, return 0.
  assert knapSack(50, [10, 20, 30], [60, 100, 120], 3)==220
  assert knapSack(0, [10, 20, 30], [60, 100, 120], 3)==0
  assert knapSack(50, [], [], 0)==0
  assert knapSack(50, [5, 6, 7], [20, 30, 40], 3)==70
  assert knapSack(10, [5, 6, 7], [20, 30, 40], 3)==50
output: def knapSack(W, wt, val, n):
      if n == 0:
          return 0
      dp = [[0 for _ in range(W + 1)] for _ in range(n + 1)]
      for i in range(n + 1):
          for w in range(W + 1):
              if i == 0 or w == 0:
                  dp[i][w] = 0
              elif wt[i-1] <= w:
                  dp[i][w] = max(val[i-1] + dp[i-1][w-wt[i-1]], dp[i-1][w])
              else:
                  dp[i][w] = dp[i-1][w]
      return dp[n][W]