Reshape the Matrix
<p>In MATLAB, there is a handy function called <code>reshape</code> which can reshape an <code>m x n</code> matrix into a new one with a different size <code>r x c</code> keeping its original data.</p>

<p>You are given an <code>m x n</code> matrix <code>mat</code> and two integers <code>r</code> and <code>c</code> representing the number of rows and the number of columns of the wanted reshaped matrix.</p>

<p>The reshaped matrix should be filled with all the elements of the original matrix in the same row-traversing order as they were.</p>

<p>If the <code>reshape</code> operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0500-0599/0566.Reshape%20the%20Matrix/images/reshape1-grid.jpg" style="width: 613px; height: 173px;" />
<pre>
<strong>Input:</strong> mat = [[1,2],[3,4]], r = 1, c = 4
<strong>Output:</strong> [[1,2,3,4]]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0500-0599/0566.Reshape%20the%20Matrix/images/reshape2-grid.jpg" style="width: 453px; height: 173px;" />
<pre>
<strong>Input:</strong> mat = [[1,2],[3,4]], r = 2, c = 4
<strong>Output:</strong> [[1,2],[3,4]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == mat.length</code></li>
	<li><code>n == mat[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 100</code></li>
	<li><code>-1000 &lt;= mat[i][j] &lt;= 1000</code></li>
	<li><code>1 &lt;= r, c &lt;= 300</code></li>
</ul>
Array; Matrix; Simulation
impl Solution {
    pub fn matrix_reshape(mat: Vec<Vec<i32>>, r: i32, c: i32) -> Vec<Vec<i32>> {
        let r = r as usize;
        let c = c as usize;
        let m = mat.len();
        let n = mat[0].len();
        if m * n != r * c {
            return mat;
        }
        let mut i = 0;
        let mut j = 0;
        (0..r)
            .into_iter()
            .map(|_| {
                (0..c)
                    .into_iter()
                    .map(|_| {
                        let res = mat[i][j];
                        j += 1;
                        if j == n {
                            j = 0;
                            i += 1;
                        }
                        res
                    })
                    .collect()
            })
            .collect()
    }
}
