day6

1 files changed, 85 insertions, 0 deletions

diff --git a/day06/solution.zig b/day06/solution.zig
new file mode 100644
index 0000000..a66268d
--- /dev/null
+++ b/day06/solution.zig
@@ -0,0 +1,85 @@
+const std = @import("std");
+const print = std.debug.print;
+const assert = std.debug.assert;
+const ArrayList = std.ArrayList;
+const HashMap = std.HashMap;
+const mem = std.mem;
+
+const fin = mem.trim(u8, @embedFile("./input.txt"), &std.ascii.whitespace);
+var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+const allocator = gpa.allocator();
+
+fn evalutate(rd: i64, rt: i64) u64 {
+    var timesBeat: u64 = 0;
+
+    for (1..@bitCast(rt + 1)) |tt| {
+        const t: i64 = @bitCast(tt);
+        const d = t * rt - t * t;
+
+        if (d > rd) {
+            timesBeat += 1;
+        }
+    }
+
+    assert(timesBeat != 0);
+    return timesBeat;
+}
+
+pub fn part1(recTimes: []const i64, recDists: []const i64) void {
+    var ans: u64 = 1;
+
+    for (recDists, recTimes) |rd, rt| {
+        ans *= evalutate(rd, rt);
+    }
+
+    print("{d}\n", .{ans});
+}
+
+pub fn part2(recTimes: []const []const u8, recDists: []const []const u8) void {
+    const rtStr = mem.concat(allocator, u8, recTimes) catch unreachable;
+    const rdStr = mem.concat(allocator, u8, recDists) catch unreachable;
+    defer {
+        allocator.free(rtStr);
+        allocator.free(rdStr);
+    }
+
+    const rt = std.fmt.parseInt(i64, rtStr, 10) catch unreachable;
+    const rd = std.fmt.parseInt(i64, rdStr, 10) catch unreachable;
+
+    const ans = evalutate(rd, rt);
+
+    print("{d}\n", .{ans});
+}
+
+pub fn main() !void {
+    var recTimes = ArrayList(i64).init(allocator);
+    var recDists = ArrayList(i64).init(allocator);
+    var recTimesStr = ArrayList([]const u8).init(allocator);
+    var recDistsStr = ArrayList([]const u8).init(allocator);
+    defer {
+        recTimes.deinit();
+        recDists.deinit();
+        recTimesStr.deinit();
+        recDistsStr.deinit();
+    }
+
+    var splitLines = mem.splitScalar(u8, fin, '\n');
+    var timesText = mem.splitScalar(u8, splitLines.next().?, ' ');
+    var distsText = mem.splitScalar(u8, splitLines.next().?, ' ');
+
+    _ = timesText.next().?;
+    _ = distsText.next().?;
+
+    while (timesText.next()) |time| {
+        try recTimes.append(std.fmt.parseInt(i64, time, 10) catch continue);
+        try recTimesStr.append(time);
+    }
+
+    while (distsText.next()) |dist| {
+        try recDists.append(std.fmt.parseInt(i64, dist, 10) catch continue);
+        try recDistsStr.append(dist);
+    }
+
+    part1(recTimes.items, recDists.items);
+    part2(recTimesStr.items, recDistsStr.items);
+}