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# 1074. Number of Submatrices That Sum to Target

<https://leetcode.com/problems/number-of-submatrices-that-sum-to-target>

## Description

Given a `matrix` and a `target`, return the number of non-empty submatrices that sum to target.

A submatrix `x1, y1, x2, y2` is the set of all cells `matrix[x][y]` with `x1 <= x <= x2` and `y1 <= y <= y2`.

Two submatrices `(x1, y1, x2, y2)` and `(x1', y1', x2', y2')` are different if they have some coordinate that is different: for example, if `x1 != x1'`.

**Example 1:**

![](https://assets.leetcode.com/uploads/2020/09/02/mate1.jpg)

```
**Input:** matrix = [[0,1,0],[1,1,1],[0,1,0]], target = 0
**Output:** 4
**Explanation:** The four 1x1 submatrices that only contain 0.
```

**Example 2:**

```
**Input:** matrix = [[1,-1],[-1,1]], target = 0
**Output:** 5
**Explanation:** The two 1x2 submatrices, plus the two 2x1 submatrices, plus the 2x2 submatrix.
```

**Example 3:**

```
**Input:** matrix = [[904]], target = 0
**Output:** 0
```

**Constraints:**

* `1 <= matrix.length <= 100`
* `1 <= matrix[0].length <= 100`
* `-1000 <= matrix[i] <= 1000`
* `-10^8 <= target <= 10^8`

## ac

```java
```