2086. Minimum Number of Food Buckets to Feed the Hamsters

Problem Link

Description

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You are given a 0-indexed string hamsters where hamsters[i] is either:

• 'H' indicating that there is a hamster at index i, or
• '.' indicating that index i is empty.

You will add some number of food buckets at the empty indices in order to feed the hamsters. A hamster can be fed if there is at least one food bucket to its left or to its right. More formally, a hamster at index i can be fed if you place a food bucket at index i - 1 and/or at index i + 1.

Return the minimum number of food buckets you should place at empty indices to feed all the hamsters or -1 if it is impossible to feed all of them.

 

Example 1:

Input: hamsters = "H..H"
Output: 2
Explanation: We place two food buckets at indices 1 and 2.
It can be shown that if we place only one food bucket, one of the hamsters will not be fed.

Example 2:

Input: hamsters = ".H.H."
Output: 1
Explanation: We place one food bucket at index 2.

Example 3:

Input: hamsters = ".HHH."
Output: -1
Explanation: If we place a food bucket at every empty index as shown, the hamster at index 2 will not be able to eat.

 

Constraints:

• 1 <= hamsters.length <= 105
• hamsters[i] is either'H' or '.'.

Solution

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Python3

class Solution:
    def minimumBuckets(self, s: str) -> int:
        s = list(s)
        n = len(s)
        
        for i, x in enumerate(s):
            if x != "H": continue
            if i - 1 >= 0 and s[i - 1] == "B": continue
                
            if i + 1 < n and s[i + 1] == ".":
                s[i + 1] = "B"
            elif i - 1 >= 0 and s[i - 1] == ".":
                s[i - 1] = "B"
            else:
                return -1
            
        return s.count("B")