In MATLAB, there is a very useful function called 'reshape', which can reshape a matrix into a new one with different size but keep its original data.

You're given a matrix represented by a two-dimensional array, and two **positive** integers **r** and **c** representing the **row** number and **column** number of the wanted reshaped matrix, respectively.

The reshaped matrix need to be filled with all the elements of the original matrix in the same **row-traversing** order as they were.

If the 'reshape' operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.

**Example 1:**

Input:nums = [[1,2], [3,4]] r = 1, c = 4Output:[[1,2,3,4]]Explanation:

Therow-traversingof nums is [1,2,3,4]. The new reshaped matrix is a 1 * 4 matrix, fill it row by row by using the previous list.

**Example 2:**

Input:nums = [[1,2], [3,4]] r = 2, c = 4Output:[[1,2], [3,4]]Explanation:

There is no way to reshape a 2 * 2 matrix to a 2 * 4 matrix. So output the original matrix.

**Note:**

- The height and width of the given matrix is in range [1, 100].
- The given r and c are all positive.

```
struct Solution;
impl Solution {
fn matrix_reshape(nums: Vec<Vec<i32>>, r: i32, c: i32) -> Vec<Vec<i32>> {
let n = nums.len();
let m = nums[0].len();
let r = r as usize;
let c = c as usize;
if n * m != r as usize * c as usize {
return nums;
}
let mut res: Vec<Vec<i32>> = vec![vec![0; c]; r];
for i in 0..n {
for j in 0..m {
let k = i * m + j;
res[k / c][k % c] = nums[i][j];
}
}
res
}
}
#[test]
fn test() {
let nums: Vec<Vec<i32>> = vec_vec_i32![[1, 2], [3, 4]];
let res: Vec<Vec<i32>> = vec_vec_i32![[1, 2, 3, 4]];
assert_eq!(Solution::matrix_reshape(nums, 1, 4), res);
}
```