Add 2021 - Day 3 - Part 1

.idea/runConfigurations/2021___Day_03.xml

@@ -0,0 +1,11 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="2021 - Day 03" type="JetRunConfigurationType">
+    <option name="MAIN_CLASS_NAME" value="MainKt" />
+    <module name="Advent_of_Code.2021-03" />
+    <shortenClasspath name="NONE" />
+    <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/2021/03" />
+    <method v="2">
+      <option name="Make" enabled="true" />
+    </method>
+  </configuration>
+</component>

2021/03/main.kt

@@ -0,0 +1,19 @@
+import java.io.File
+
+fun main() {
+	val lines = File("input/1.txt").readLines().filter(String::isNotEmpty)
+	
+	val totalRows = lines.size
+	val totalColumns = lines[0].length
+	val totalOnesPerColumn = Array(totalColumns) { column ->
+		lines.count { it[column] == '1' }
+	}
+	
+	val gammaRate = totalOnesPerColumn
+		.map { if (it > totalRows / 2) 1 else 0 }
+		.foldIndexed(0) { index, total, bit -> total or (bit shl (totalColumns - index - 1)) }
+	
+	val epsilonRate = gammaRate xor ((1 shl totalColumns) - 1)
+	
+	println("Power consumption: ${gammaRate * epsilonRate}")
+}

README.md

@@ -32,3 +32,4 @@ The versions should not matter, but I used Visual Studio 2019 with `MSVC v142 (1
 | 2015 |  01 | NASM x86 |
 | 2021 |  01 | Kotlin   |
 | 2021 |  02 | Kotlin   |
+| 2021 |  03 | Kotlin   |

build.gradle.kts

@@ -34,4 +34,5 @@ sourceSets {
 	
 	make(2021, 1)
 	make(2021, 2)
+	make(2021, 3)
 }