advent-of-code

commit 92598356e7eff827764bfcba8040f0cb03f31a82
parent 9a0ed8a812d5e8f4e949394a0edcc56966a878cb
Author: Amin Mesbah <dev@aminmesbah.com>
Date:   Sun,  1 Dec 2019 20:20:51 -0800

Add solution for 2019 01-2

Diffstat:
M
day01_1.zig
 | 
42
++++++++++++++++++++++++++++++++++--------

1 file changed, 34 insertions(+), 8 deletions(-)
diff --git a/day01_1.zig b/day01_1.zig
@@ -2,16 +2,20 @@ const std = @import("std");
 const dbg = std.debug;
 
 pub fn main() void {
-    var total_fuel: u32 = 0;
-    for (input) |mass, i| {
-        var module_fuel = get_fuel(mass);
-        total_fuel += module_fuel;
+    var fuel_for_module_mass: i32 = 0;
+    var fuel_for_total_mass: i32 = 0;
+    for (input) |mass| {
+        var module_mass_fuel = get_fuel(mass);
+        var total_fuel = get_total_module_fuel(mass);
+        fuel_for_module_mass += module_mass_fuel;
+        fuel_for_total_mass += total_fuel;
     }
-    dbg.warn("Total fuel: {}\n", total_fuel);
+    dbg.warn("01-1 Total fuel for the modules: {}\n", fuel_for_module_mass);
+    dbg.warn("01-2 Total fuel for the modules and fuel: {}\n", fuel_for_total_mass);
 }
 
-fn get_fuel(mass: u32) u32 {
-    return (mass / 3) - 2;
+fn get_fuel(mass: i32) i32 {
+    return @divFloor(mass, 3) - 2;
 }
 
 test "get fuel" {
@@ -21,7 +25,29 @@ test "get fuel" {
     dbg.assert(get_fuel(100756) == 33583);
 }
 
-const input = [_]u32{
+fn get_total_module_fuel(module_mass: i32) i32 {
+    const module_fuel_mass = get_fuel(module_mass);
+    var unfueled_fuel = module_fuel_mass;
+    var fuel_fuel_mass: i32 = 0;
+    while (unfueled_fuel > 0) {
+        // "fuel" is a really strange word
+        var fuel_for_fuel = get_fuel(unfueled_fuel);
+        if (fuel_for_fuel <= 0) {
+            break;
+        }
+        fuel_fuel_mass += fuel_for_fuel;
+        unfueled_fuel = fuel_for_fuel;
+    }
+    return module_fuel_mass + fuel_fuel_mass;
+}
+
+test "get total module fuel" {
+    dbg.assert(get_total_module_fuel(14) == 2);
+    dbg.assert(get_total_module_fuel(1969) == 966);
+    dbg.assert(get_total_module_fuel(100756) == 50346);
+}
+
+const input = [_]i32{
     91617,
     134652,
     101448,