You are given a string s consisting of lowercase English letters and the character '?'.

For any string, the cost of the character at index i is defined as the number of times the character s[i] appears before index i (that is, at indices $j < i$). The total value of the string is the sum of the costs across all indices from $0$ to s.length $- 1$.

Replace every '?' in s with a lowercase English letter such that the total value of the string is minimized. If there are multiple strings that achieve the minimum total value, return the lexicographically smallest one.

Constraints:

• $1 \leq$ s.length $\leq 10^5$

• s[i] is either a lowercase English letter or '?'.

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.