# 1252. Cells with Odd Values in a Matrix

https://leetcode.com/problems/cells-with-odd-values-in-a-matrix

## Description

There is an `m x n` matrix that is initialized to all `0`'s. There is also a 2D array `indices` where each `indices[i] = [ri, ci]` represents a **0-indexed location** to perform some increment operations on the matrix.

For each location `indices[i]`, do **both** of the following:

1. Increment **all** the cells on row `ri`.
2. Increment **all** the cells on column `ci`.

Given `m`, `n`, and `indices`, return _the **number of odd-valued cells** in the matrix after applying the increment to all locations in_ `indices`.

**Example 1:**

![](https://assets.leetcode.com/uploads/2019/10/30/e1.png)

```
**Input:** m = 2, n = 3, indices = [[0,1],[1,1]]
**Output:** 6
**Explanation:** Initial matrix = [[0,0,0],[0,0,0]].
After applying first increment it becomes [[1,2,1],[0,1,0]].
The final matrix is [[1,3,1],[1,3,1]], which contains 6 odd numbers.
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2019/10/30/e2.png)

```
**Input:** m = 2, n = 2, indices = [[1,1],[0,0]]
**Output:** 0
**Explanation:** Final matrix = [[2,2],[2,2]]. There are no odd numbers in the final matrix.
```

**Constraints:**

* `1 <= m, n <= 50`
* `1 <= indices.length <= 100`
* `0 <= ri < m`
* `0 <= ci < n`

**Follow up:** Could you solve this in `O(n + m + indices.length)` time with only `O(n + m)` extra space?

## ac

```java
```
