Added first day in zig

1 files changed, 30 insertions, 0 deletions

diff --git a/2021/01/second.zig b/2021/01/second.zig
new file mode 100644
index 0000000..eb6993e
--- /dev/null
+++ b/2021/01/second.zig
@@ -0,0 +1,30 @@
+const std = @import("std");
+
+const example = @embedFile("example");
+const input = @embedFile("input");
+
+pub fn main() anyerror!void {
+    try std.testing.expectEqual(solve(example), 5);
+    const result = try solve(input);
+    try std.io.getStdOut().writer().print("{}\n", .{result});
+}
+
+fn solve(puzzle: []const u8) !u64 {
+    var it = std.mem.tokenize(u8, puzzle, " \n");
+    var tot: u64 = 0;
+    var prev = [_]?u64{null} ** 3;
+    while (it.next()) |value| {
+        const n = try std.fmt.parseInt(u64, value, 10);
+        if (prev[0]) |p| {
+            if (p < n) {
+                tot += 1;
+            }
+        }
+        var i: usize = 0;
+        while (i < prev.len - 1) : (i += 1) {
+            prev[i] = prev[i + 1];
+        }
+        prev[2] = n;
+    }
+    return tot;
+}