07: part1+2 (zig)

7/solve.zig

@@ -0,0 +1,49 @@
+const std = @import("std");
+
+pub fn main() !void {
+    var alloc = std.heap.GeneralPurposeAllocator(.{}){};
+    defer std.debug.assert(!alloc.deinit());
+    var gpa = &alloc.allocator;
+
+    var crabs = std.ArrayList(i32).init(gpa);
+    defer crabs.deinit();
+
+    const stdin = std.io.getStdIn().reader();
+
+    var topCrab: i32 = 0;
+    var tmp: [32]u8 = undefined;
+    while (try stdin.readUntilDelimiterOrEof(&tmp, ',')) |line| {
+        var newLine = if (line[line.len-1] == '\n') line[0..line.len-1] else line;
+        const crab = try std.fmt.parseInt(i32, newLine, 10);
+        try crabs.append(crab);
+
+        if (crab > topCrab) {
+            topCrab = crab;
+        }
+    }
+
+    var bestFuel1: u32 = std.math.maxInt(u32);
+    var bestFuel2: u32 = std.math.maxInt(u32);
+
+    var i: i32 = 0;
+    while (i < topCrab): (i += 1) {
+        var fuel1: u32 = 0;
+        var fuel2: u32 = 0;
+
+        for (crabs.items) |crab| {
+            var steps = @intCast(u32, try std.math.absInt(crab - i));
+            fuel1 += steps;
+            fuel2 += @divTrunc(steps * (steps + 1), 2);
+        }
+
+        if (fuel1 < bestFuel1) {
+            bestFuel1 = fuel1;
+        }
+        if (fuel2 < bestFuel2) {
+            bestFuel2 = fuel2;
+        }
+    }
+
+    std.debug.print("{}\n", .{bestFuel1});
+    std.debug.print("{}\n", .{bestFuel2});
+}