day 10 finally

day10/src/Main.kt

@@ -1,3 +1,71 @@
+import Instruction.Type.*
+import java.io.File
+
+const val limit = 300;
+data class Instruction(val type: Type, val value: Int) {
+
+    enum class Type {
+        NOOP,
+        ADDX
+    }
+}
+
 fun main() {
-    println("Hello World!")
+    val instructions  = MutableList<Instruction>(0) { Instruction(NOOP, 0) };
+
+    val cyclesOfInterest = setOf(20, 60, 100, 140, 180, 220)
+    for (line in File("c.input").readLines()) {
+        if (line.isEmpty()) continue;
+        val s = line.split(" ");
+        if (s[0] == "noop") {
+            instructions.add(Instruction(NOOP, 0));
+        }
+        if (s[0] == "addx") {
+            instructions.add(Instruction(ADDX, s[1].toInt()));
+        }
+    }
+    for (i in instructions) {
+        println("$i")
+    }
+
+    var signalSum = 0;
+
+    var cycle = 0;
+    var pc = 0;
+    var x = 1;
+    var command = instructions[cycle];
+    var currentTimer = 0;
+    while (cycle < limit) {
+        // At the start of the first cycle, the noop instruction begins execution.
+        if (cycle % 40 == 0) print("\n")
+        if (currentTimer == 0) {
+            command = instructions[pc % instructions.count()]
+            when (command.type) {
+                NOOP -> currentTimer = 1
+                ADDX -> currentTimer = 2
+            }
+        }
+
+        // During the first cycle, X is 1.
+        val spriteLocations = setOf(x-1, x, x+1)
+        if (cycle % 40 in spriteLocations) print("#")
+        else print(".")
+        //println("during cycle ${cycle+1}, we're executing $command the register is $x")
+        signalSum += (cycle+1) * x
+
+        // After the first cycle, the noop instruction finishes execution, doing nothing.
+        currentTimer -= 1
+        if (currentTimer == 0) {
+            // if the timer is at zero, we execute the existing command.
+            when (command.type) {
+                NOOP -> {}
+                ADDX -> x += command.value
+            }
+            pc++
+        }
+
+        cycle += 1
+    }
+
+    println("after all is said and done,, the sum is $signalSum")
 }