public class Solution
extends Object
2023 - Number of Pairs of Strings With Concatenation Equal to Target\.
Medium
Given an array of **digit** strings `nums` and a **digit** string `target`, return _the number of pairs of indices_ `(i, j)` _(where_ `i != j`_) such that the **concatenation** of_ `nums[i] + nums[j]` _equals_ `target`.
**Example 1:**
**Input:** nums = ["777","7","77","77"], target = "7777"
**Output:** 4
**Explanation:** Valid pairs are:
- (0, 1): "777" + "7"
- (1, 0): "7" + "777"
- (2, 3): "77" + "77"
- (3, 2): "77" + "77"
**Example 2:**
**Input:** nums = ["123","4","12","34"], target = "1234"
**Output:** 2
**Explanation:** Valid pairs are:
- (0, 1): "123" + "4"
- (2, 3): "12" + "34"
**Example 3:**
**Input:** nums = ["1","1","1"], target = "11"
**Output:** 6
**Explanation:** Valid pairs are:
- (0, 1): "1" + "1"
- (1, 0): "1" + "1"
- (0, 2): "1" + "1"
- (2, 0): "1" + "1"
- (1, 2): "1" + "1"
- (2, 1): "1" + "1"
**Constraints:**
* `2 <= nums.length <= 100`
* `1 <= nums[i].length <= 100`
* `2 <= target.length <= 100`
* `nums[i]` and `target` consist of digits.
* `nums[i]` and `target` do not have leading zeros.