function matrixReshape(mat,r,c){
 const m=mat.length,n=mat[0].length;
 if(m*n!==r*c) return mat;
 const flat=mat.flat();
 const out=[];
 for(let i=0;i<r;i++) out.push(flat.slice(i*c,(i+1)*c));
 return out;
}

function matrixReshape(mat:number[][], r:number, c:number):number[][]{
 const m=mat.length,n=mat[0].length;
 if(m*n!==r*c) return mat;
 const flat:number[]=mat.flat();
 const out:number[][]=[];
 for(let i=0;i<r;i++) out.push(flat.slice(i*c,(i+1)*c));
 return out;
}

package main

func matrixReshape(mat [][]int, r int, c int) [][]int {
	m, n := len(mat), len(mat[0])
	if m*n != r*c {
		return mat
	}

	flat := make([]int, 0, m*n)
	for i := 0; i < m; i++ {
		flat = append(flat, mat[i]...)
	}

	out := make([][]int, r)
	for i := 0; i < r; i++ {
		out[i] = flat[i*c : (i+1)*c]
	}
	return out
}

func main() {}

fn matrix_reshape(mat: Vec<Vec<i32>>, r: usize, c: usize) -> Vec<Vec<i32>> {
	let m = mat.len();
	let n = mat[0].len();
	if m * n != r * c {
		return mat;
	}
	let flat: Vec<i32> = mat.into_iter().flatten().collect();
	(0..r).map(|i| flat[i*c..(i+1)*c].to_vec()).collect()
}
fn main() {}