# 1794. Count Pairs of Equal Substrings With Minimum Difference

https://leetcode.com/problems/count-pairs-of-equal-substrings-with-minimum-difference

## Description

You are given two strings `firstString` and `secondString` that are **0-indexed** and consist only of lowercase English letters. Count the number of index quadruples `(i,j,a,b)` that satisfy the following conditions:

* `0 <= i <= j < firstString.length`
* `0 <= a <= b < secondString.length`
* The substring of `firstString` that starts at the `ith` character and ends at the `jth` character (inclusive) is **equal** to the substring of `secondString` that starts at the `ath` character and ends at the `bth` character (inclusive).
* `j - a` is the **minimum** possible value among all quadruples that satisfy the previous conditions.

Return _the **number** of such quadruples_.

**Example 1:**

```
**Input:** firstString = "abcd", secondString = "bccda"
**Output:** 1
**Explanation:** The quadruple (0,0,4,4) is the only one that satisfies all the conditions and minimizes j - a.
```

**Example 2:**

```
**Input:** firstString = "ab", secondString = "cd"
**Output:** 0
**Explanation:** There are no quadruples satisfying all the conditions.
```

**Constraints:**

* `1 <= firstString.length, secondString.length <= 2 * 105`
* Both strings consist only of lowercase English letters.

## ac

```java
```
