# 1764. Form Array by Concatenating Subarrays of Another Array

https://leetcode.com/problems/form-array-by-concatenating-subarrays-of-another-array

## Description

You are given a 2D integer array `groups` of length `n`. You are also given an integer array `nums`.

You are asked if you can choose `n` **disjoint** subarrays from the array `nums` such that the `ith` subarray is equal to `groups[i]` (**0-indexed**), and if `i > 0`, the `(i-1)th` subarray appears **before** the `ith` subarray in `nums` (i.e. the subarrays must be in the same order as `groups`).

Return `true` _if you can do this task, and_ `false` _otherwise_.

Note that the subarrays are **disjoint** if and only if there is no index `k` such that `nums[k]` belongs to more than one subarray. A subarray is a contiguous sequence of elements within an array.

**Example 1:**

```
**Input:** groups = [[1,-1,-1],[3,-2,0]], nums = [1,-1,0,1,-1,-1,3,-2,0]
**Output:** true
**Explanation:** You can choose the 0th subarray as [1,-1,0,**1,-1,-1**,3,-2,0] and the 1st one as [1,-1,0,1,-1,-1,**3,-2,0**].
These subarrays are disjoint as they share no common nums[k] element.
```

**Example 2:**

```
**Input:** groups = [[10,-2],[1,2,3,4]], nums = [1,2,3,4,10,-2]
**Output:** false
**Explanation:** Note that choosing the subarrays [**1,2,3,4**,10,-2] and [1,2,3,4,**10,-2**] is incorrect because they are not in the same order as in groups.
[10,-2] must come before [1,2,3,4].
```

**Example 3:**

```
**Input:** groups = [[1,2,3],[3,4]], nums = [7,7,1,2,3,4,7,7]
**Output:** false
**Explanation:** Note that choosing the subarrays [7,7,**1,2,3**,4,7,7] and [7,7,1,2,**3,4**,7,7] is invalid because they are not disjoint.
They share a common elements nums[4] (0-indexed).
```

**Constraints:**

* `groups.length == n`
* `1 <= n <= 103`
* `1 <= groups[i].length, sum(groups[i].length) <= 103`
* `1 <= nums.length <= 103`
* `-107 <= groups[i][j], nums[k] <= 107`

## ac

```java
```
