Is Minimum Deletion Cost to Make All Characters Equal easy or hard?

The problem is typically classified as Medium. The implementation is straightforward once you recognize that the optimal strategy is to keep one character type and delete the rest. The challenge lies in identifying the cost-aggregation trick that reduces the problem to a single pass.

Minimum Deletion Cost to Make All Characters Equal Python/Java solution

The solution iterates through the string and stores the total deletion cost per character in a dictionary (Python) or HashMap (Java). After computing the total cost of all characters, subtract the maximum stored value from the total. This produces the minimum cost needed to delete the remaining characters.

How to solve Minimum Deletion Cost to Make All Characters Equal in O(n)?

Traverse the string once and use a hash map to sum the deletion cost for each character. Also compute the total cost of all characters. The minimum deletion cost equals totalCost minus the maximum accumulated cost of any single character. This keeps the most valuable character group and deletes the rest.

What is the best approach for Minimum Deletion Cost to Make All Characters Equal?

The optimal approach is grouping characters using a hash map and enumerating which character to keep. First compute the total deletion cost of the string, then track the total cost associated with each character. Keeping the character with the maximum accumulated cost minimizes deletions. This runs in O(n) time with O(k) extra space, where k is the number of distinct characters.

Is Minimum Deletion Cost to Make All Characters Equal asked at Google/Amazon/Meta?

Problems based on cost minimization, string grouping, and hash map aggregation frequently appear in interviews at companies like Amazon, Google, and Meta. Variants often involve choosing a target value and minimizing operations or costs across the rest of the array or string.

What data structure is used in Minimum Deletion Cost to Make All Characters Equal?

The core data structure is a hash table (hash map) that groups characters and accumulates their total deletion costs. This allows constant-time updates while iterating through the string and makes it easy to evaluate which character should be kept.

What is the time complexity of Minimum Deletion Cost to Make All Characters Equal?

The optimal solution runs in O(n) time because the string is scanned once to accumulate costs per character. A second pass over the distinct characters determines the minimum deletion cost. Space complexity is O(k) for storing cost totals of each unique character.

Description Hints 1 Solution Video 8:59

3784. Minimum Deletion Cost to Make All Characters Equal

Medium55.0% acceptance

You are given a string s of length n and an integer array cost of the same length, where cost[i] is the cost to delete the i^th character of s.

You may delete any number of characters from s (possibly none), such that the resulting string is non-empty and consists of equal characters.

Return an integer denoting the minimum total deletion cost required.

Example 1:

Input: s = "aabaac", cost = [1,2,3,4,1,10]

Output: 11

Explanation:

Deleting the characters at indices 0, 1, 2, 3, 4 results in the string "c", which consists of equal characters, and the total cost is cost[0] + cost[1] + cost[2] + cost[3] + cost[4] = 1 + 2 + 3 + 4 + 1 = 11.

Example 2:

Input: s = "abc", cost = [10,5,8]

Output: 13

Explanation:

Deleting the characters at indices 1 and 2 results in the string "a", which consists of equal characters, and the total cost is cost[1] + cost[2] = 5 + 8 = 13.

Example 3:

Input: s = "zzzzz", cost = [67,67,67,67,67]

Output: 0

Explanation:

All characters in s are equal, so the deletion cost is 0.

Constraints:

n == s.length == cost.length
1 <= n <= 10⁵
1 <= cost[i] <= 10⁹
s consists of lowercase English letters.

Topics

Hints open one at a time

Hint 1

Keep the character whose total deletion cost is maximum

8:59

Still stuck?Read the written solution, or watch a walkthrough.

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1class Solution:
2    def minCost(self, s: str, cost: List[int]) -> int:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

"aabaac"
[1,2,3,4,1,10]

Input

"abc"
[10,5,8]

Input

"zzzzz"
[67,67,67,67,67]

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