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# 1277. Count Square Submatrices with All Ones

<https://leetcode.com/problems/count-square-submatrices-with-all-ones>

## Description

Given a `m * n` matrix of ones and zeros, return how many **square** submatrices have all ones.

**Example 1:**

```
**Input:** matrix =
[
  [0,1,1,1],
  [1,1,1,1],
  [0,1,1,1]
]
**Output:** 15
**Explanation:** 
There are **10** squares of side 1.
There are **4** squares of side 2.
There is  **1** square of side 3.
Total number of squares = 10 + 4 + 1 = **15**.
```

**Example 2:**

```
**Input:** matrix = 
[
  [1,0,1],
  [1,1,0],
  [1,1,0]
]
**Output:** 7
**Explanation:** 
There are **6** squares of side 1.  
There is **1** square of side 2. 
Total number of squares = 6 + 1 = **7**.
```

**Constraints:**

* `1 <= arr.length <= 300`
* `1 <= arr[0].length <= 300`
* `0 <= arr[i][j] <= 1`

## ac

```java
```