Is Minimum ASCII Delete Sum for Two Strings easy or hard?

The problem is classified as Medium on LeetCode. It requires recognizing that the task is a variation of the longest common subsequence problem but with ASCII weights. Once the DP state and transitions are defined, the implementation is straightforward.

Minimum ASCII Delete Sum for Two Strings Python/Java solution

Python, Java, and C++ implementations usually follow the same bottom-up DP logic. Create a 2D array dp[m+1][n+1], initialize base cases with ASCII sums, and fill the table from the end of both strings. The final result appears at dp[0][0].

How to solve Minimum ASCII Delete Sum for Two Strings in O(n)?

The standard solution requires O(m*n) time because every pair of indices from both strings must be considered. Space can be optimized to O(n) by keeping only two rows of the DP table at a time, but the time complexity remains O(m*n). Fully reducing the time to O(n) is not possible for the general case.

What is the best approach for Minimum ASCII Delete Sum for Two Strings?

Dynamic programming is the most reliable approach. Define a DP table where dp[i][j] represents the minimum ASCII delete cost to make the suffixes of two strings equal. By comparing characters and choosing the cheaper deletion, the algorithm computes the optimal result in O(m*n) time and O(m*n) space.

Is Minimum ASCII Delete Sum for Two Strings asked at Google/Amazon/Meta?

This problem is a classic dynamic programming pattern related to longest common subsequence and edit distance. Variants of it frequently appear in interviews at companies like Amazon, Google, and Meta where candidates are expected to design a DP state and optimize overlapping subproblems.

What data structure is used in Minimum ASCII Delete Sum for Two Strings?

The core data structure is a 2D dynamic programming table that stores results for every pair of indices in the two strings. Memoization implementations use a hash map or 2D array cache, while iterative solutions use a DP matrix to store intermediate costs.

What is the time complexity of Minimum ASCII Delete Sum for Two Strings?

The optimal dynamic programming solution runs in O(m*n) time, where m and n are the lengths of the two strings. Each state (i, j) is computed once and depends on constant-time transitions from neighboring states. Space complexity is also O(m*n) for the DP table or memoization cache.

Description Hints 1 Solution Video 21:55

712. Minimum ASCII Delete Sum for Two Strings

Medium70.9% acceptance4 companies

Given two strings s1 and s2, return the lowest ASCII sum of deleted characters to make two strings equal.

Example 1:

Input: s1 = "sea", s2 = "eat"
Output: 231
Explanation: Deleting "s" from "sea" adds the ASCII value of "s" (115) to the sum.
Deleting "t" from "eat" adds 116 to the sum.
At the end, both strings are equal, and 115 + 116 = 231 is the minimum sum possible to achieve this.

Example 2:

Input: s1 = "delete", s2 = "leet"
Output: 403
Explanation: Deleting "dee" from "delete" to turn the string into "let",
adds 100[d] + 101[e] + 101[e] to the sum.
Deleting "e" from "leet" adds 101[e] to the sum.
At the end, both strings are equal to "let", and the answer is 100+101+101+101 = 403.
If instead we turned both strings into "lee" or "eet", we would get answers of 433 or 417, which are higher.

Constraints: