diff --git a/README.md b/README.md
index ac915cf..a9f4073 100644
--- a/README.md
+++ b/README.md
@@ -5,11 +5,11 @@ This repo contains my attempt at this year's Advent of Code (2023)
 I will try and do some problems (probably not all of them) in Scala
 
 ## Progress:
-#### Stars: 22 / 50
+#### Stars: 23 / 50
 |        Mon         |        Tue        |        Wed        |        Thu        |        Fri        |        Sat        |        Sun         |
 |:------------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|:------------------:|
 |                    |                   |                   |                   | 1<br>:star::star: | 2<br>:star::star: | 3<br>:star::star:  |
 | 4<br>:star::star:  | 5<br>:star::star: | 6<br>:star::star: | 7<br>:star::star: | 8<br>:star::star: | 9<br>:star::star: | 10<br>:star::star: |
-| 11<br>:star::star: |        12         |        13         |        14         |        15         |        16         |         17         |
+| 11<br>:star::star: |        12         |   13<br>:star:    |        14         |        15         |        16         |         17         |
 |         18         |        19         |        20         |        21         |        22         |        23         |         24         |
 |         25         |                   |                   |                   |                   |                   |                    |
\ No newline at end of file
diff --git a/src/day13/Puzzle1.scala b/src/day13/Puzzle1.scala
new file mode 100644
index 0000000..756e9bb
--- /dev/null
+++ b/src/day13/Puzzle1.scala
@@ -0,0 +1,92 @@
+package day13
+
+import scala.io.{BufferedSource, Source}
+
+object Puzzle1 {
+  var maps: Array[Array[Array[Boolean]]] = Array.empty
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: String = source.getLines().mkString("\n")
+
+    val mapsStr: Array[String] = lines.split("\n\n")
+    maps = new Array(mapsStr.length)
+
+    for ((mapStr: String, i: Int) <- mapsStr.zipWithIndex) {
+      val rows: Array[String] = mapStr.split("\n")
+      val map: Array[Array[Boolean]] = new Array(rows.length)
+      for ((row: String, j: Int) <- rows.zipWithIndex) {
+        map(j) = row.map(_ == '#').toArray
+      }
+      maps(i) = map
+    }
+
+    source.close()
+  }
+
+  def getReflectionValue(map: Array[Array[Boolean]]): Int = {
+    val height: Int = map.length
+    val width: Int = if (height == 0) 0 else map(0).length
+    var value: Int = 0
+
+    for (x: Int <- 0 until width-1) {
+      if (isReflection(map, x)) {
+        value += x+1
+      }
+    }
+
+    val mapT: Array[Array[Boolean]] = transpose(map)
+
+    for (y: Int <- 0 until height-1) {
+      if (isReflection(mapT, y)) {
+        value += 100*(y+1)
+      }
+    }
+
+    return value
+  }
+
+  def isReflection(map: Array[Array[Boolean]], x: Int): Boolean = {
+    for (row: Array[Boolean] <- map) {
+      val a = row.dropRight(row.length - x - 1).reverse
+      val b = row.drop(x+1)
+      for (i: Int <- 0 until Math.min(a.length, b.length)) {
+        if (a(i) != b(i)) {
+          return false
+        }
+      }
+    }
+    return true
+  }
+
+  def transpose(map: Array[Array[Boolean]]): Array[Array[Boolean]] = {
+    val height: Int = map.length
+    val width: Int = if (height == 0) 0 else map(0).length
+
+    val mapT: Array[Array[Boolean]] = Array.ofDim(width, height)
+
+    for (y: Int <- 0 until height) {
+      for (x: Int <- 0 until width) {
+        mapT(x)(y) = map(y)(x)
+      }
+    }
+
+    return mapT
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+
+    var solution: Int = 0
+
+    for (map: Array[Array[Boolean]] <- maps) {
+      solution += getReflectionValue(map)
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day13/input1.txt")
+    println(solution)
+  }
+}
diff --git a/tests/day13/Puzzle1Test.scala b/tests/day13/Puzzle1Test.scala
new file mode 100644
index 0000000..3f4548b
--- /dev/null
+++ b/tests/day13/Puzzle1Test.scala
@@ -0,0 +1,9 @@
+package day13
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day13/input1.txt") == 405)
+  }
+}
diff --git a/tests_res/day13/input1.txt b/tests_res/day13/input1.txt
new file mode 100644
index 0000000..f226414
--- /dev/null
+++ b/tests_res/day13/input1.txt
@@ -0,0 +1,15 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#
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