Day 1 done, needs some polishing

.gitignore

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+zig-cache/*
+zig-out/*

build.zig

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+const std = @import("std");
+
+pub fn build(b: *std.build.Builder) void {
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
+    const target = b.standardTargetOptions(.{});
+
+    // Standard release options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
+    const mode = b.standardReleaseOptions();
+
+    const dayPath = "src/day1.zig";
+
+    const exe = b.addExecutable("advent_of_code", dayPath);
+    exe.setTarget(target);
+    exe.setBuildMode(mode);
+    exe.install();
+
+    const run_cmd = exe.run();
+    run_cmd.step.dependOn(b.getInstallStep());
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    const exe_tests = b.addTest(dayPath);
+    exe_tests.setTarget(target);
+    exe_tests.setBuildMode(mode);
+
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&exe_tests.step);
+}

src/day1.zig

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+const std = @import("std");
+
+
+pub fn main() !void {
+    var file = try std.fs.cwd().openFile("inputs/day1.txt", .{});
+    defer file.close();
+
+    var buf_reader = std.io.bufferedReader(file.reader());
+    var in_stream = buf_reader.reader();
+
+    var buf: [1024]u8 = undefined;
+    var elf_sums: [1024]i32 = [_]i32{0} ** 1024;
+    var i: usize = 0;
+    while (try in_stream.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        if (line.len == 0) {
+            i += 1;
+        }
+        else {
+            const calorie_count = std.fmt.parseInt(i32, line, 10) catch |err| {
+                std.debug.print("Error converting str: {?}\n", .{err});
+                return;
+            };
+
+            elf_sums[i] += calorie_count;
+        }
+    }
+
+
+    std.sort.sort(i32, &elf_sums, {}, std.sort.desc(i32));
+
+    var sum: i32 = 0;
+    for (elf_sums[0..3]) |value, index| {
+        std.debug.print("Pos {} = {}\n", .{index+1, value});
+        sum += value;
+    }
+
+    std.debug.print("Total calories of the top three elves: {}\n", .{sum});
+}
+
+test "simple test" {
+    var list = std.ArrayList(i32).init(std.testing.allocator);
+    defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
+    try list.append(42);
+    try std.testing.expectEqual(@as(i32, 42), list.pop());
+}