1638. Count Substrings That Differ by One Character

https://leetcode.com/problems/count-substrings-that-differ-by-one-character

Description

Given two strings s and t, find the number of ways you can choose a non-empty substring of s and replace a single character by a different character such that the resulting substring is a substring of t. In other words, find the number of substrings in s that differ from some substring in t by exactly one character.

For example, the underlined substrings in "computer" and "computation" only differ by the 'e'/'a', so this is a valid way.

Return the number of substrings that satisfy the condition above.

A substring is a contiguous sequence of characters within a string.

Example 1:

**Input:** s = "aba", t = "baba"
**Output:** 6
**Explanation:** The following are the pairs of substrings from s and t that differ by exactly 1 character:
("aba", "baba")
("aba", "baba")
("aba", "baba")
("aba", "baba")
("aba", "baba")
("aba", "baba")
The underlined portions are the substrings that are chosen from s and t.

​​Example 2:

**Input:** s = "ab", t = "bb"
**Output:** 3
**Explanation:** The following are the pairs of substrings from s and t that differ by 1 character:
("ab", "bb")
("ab", "bb")
("ab", "bb")
​​​​The underlined portions are the substrings that are chosen from s and t.

Example 3:

**Input:** s = "a", t = "a"
**Output:** 0

Example 4:

**Input:** s = "abe", t = "bbc"
**Output:** 10

Constraints:

• 1 <= s.length, t.length <= 100

• s and t consist of lowercase English letters only.

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