From 365cacbd42cdf82126a1ee92edaf1f6c2e6a67a3 Mon Sep 17 00:00:00 2001
From: Gleb Koval <gleb@koval.net>
Date: Tue, 31 May 2022 22:54:52 +0100
Subject: [PATCH] reshape-the-matrix

---
 reshape-the-matrix/sol_functional.rs | 20 ++++++++++++++++++++
 reshape-the-matrix/sol_loops.rs      | 17 +++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 reshape-the-matrix/sol_functional.rs
 create mode 100644 reshape-the-matrix/sol_loops.rs

diff --git a/reshape-the-matrix/sol_functional.rs b/reshape-the-matrix/sol_functional.rs
new file mode 100644
index 0000000..c52de94
--- /dev/null
+++ b/reshape-the-matrix/sol_functional.rs
@@ -0,0 +1,20 @@
+// This is a more functional solution that I think
+// is a bit easier to read, but does iterate over
+// the matrix twice (two `Iter.collect()`s). So without
+// compiler optimisations it might be a bit slower.
+//
+// I don't actually know whether this is true or not.
+impl Solution {
+    pub fn matrix_reshape(mat: Vec<Vec<i32>>, r: i32, c: i32) -> Vec<Vec<i32>> {
+        let (m, n) = (mat.len(), mat[0].len());
+        if m*n != (r*c) as usize || m == r as usize{
+            return mat;
+        }
+        mat.into_iter()
+            .flatten()
+            .collect::<Vec<_>>()
+            .chunks(c as usize)
+            .map(|row| row.to_vec())
+            .collect::<Vec<_>>()
+    }
+}
\ No newline at end of file
diff --git a/reshape-the-matrix/sol_loops.rs b/reshape-the-matrix/sol_loops.rs
new file mode 100644
index 0000000..d40ab58
--- /dev/null
+++ b/reshape-the-matrix/sol_loops.rs
@@ -0,0 +1,17 @@
+// A solution using loops and still pretty
+// easy to understand, and iterates over the
+// matrix only once.
+impl Solution {
+    pub fn matrix_reshape(mat: Vec<Vec<i32>>, r: i32, c: i32) -> Vec<Vec<i32>> {
+        let (m, n) = (mat.len(), mat[0].len());
+        let (r, c) = (r as usize, c as usize);
+        if m*n != r*c || m == r {
+            return mat;
+        }
+        let mut reshaped_matrix = vec![vec![0; c]; r];
+        for idx in (0..m*n) {
+            reshaped_matrix[idx / c][idx % c] = mat[idx / n][idx % n];
+        }
+        reshaped_matrix
+    }
+}
\ No newline at end of file