Largest Values From Labels in Python

Suppose we have a set of items: the i-th item has value values[i] and label labels[i]. Then, we will take a subset S of these items, such that −

• |S| <= num_wanted
• For every label L, the number of items present in S with label L is <= use_limit.

We have to find the largest possible sum of the subset S.

For example, if the input is like values = [5,4,3,2,1] and labels are [1,1,2,2,3], num_wanted = 3, use_limit = 1, then the output will be 9. This is because the subset chosen in the first, third and fifth item.

To solve this, we will follow these steps −

• make one array v
• for i in range 0 to length of values
  • insert [values[i], labels[i]] into v
• sort the v array
• ans := 0, use := empty map, and i := 0
• while num_wanted and i < length of v
  • if v[i, 1] is not present in use map
    • decrease num_wanted by 1
    • ans := ans + v[i, 0]
    • use[v[i, 1]] := 1
  • else use[v[i, 1]] < use_limit
    • decrease num_wanted by 1
    • ans := ans + v[i, 0]
    • increase use[v[i, 1]] by 1
  • increase i by 1
• return ans

Let us see the following implementation to get better understanding −

Example

 Live Demo

class Solution(object):
   def largestValsFromLabels(self, values, labels, num_wanted, use_limit):
      v = []
      for i in range(len(values)):
         v.append([values[i],labels[i]])
      v = sorted(v,key = lambda v:v[0],reverse=True)
      ans = 0
      use = {}
      i = 0
      while num_wanted and i < len(v):
         if v[i][1] not in use:
            num_wanted -=1
            ans+=v[i][0]
            use[v[i][1]] = 1
         elif use[v[i][1]]<use_limit:
            num_wanted -=1
            ans+=v[i][0]
            use[v[i][1]]+=1
         i+=1
      return ans
ob = Solution()
print(ob.largestValsFromLabels([5,4,3,2,1],[1,1,2,2,3],3,1))

Input

[5,4,3,2,1]
[1,1,2,2,3]
3
1

Output

9

Arnab Chakraborty

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Updated on: 30-Apr-2020

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