53 lines
1.3 KiB
Zig
53 lines
1.3 KiB
Zig
const std = @import("std");
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const print = std.debug.print;
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const file = @embedFile("input");
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pub fn main() !void {
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var left: [1000]i32 = undefined;
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var right: [1000]i32 = undefined;
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var i: u32 = 0;
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var iter = std.mem.split(u8, file, "\n");
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while (iter.next()) |line| {
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if (i == 1000) continue;
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left[i] = try std.fmt.parseInt(i32, line[0..5], 10);
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right[i] = try std.fmt.parseInt(i32, line[8..13], 10);
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i += 1;
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}
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try std.testing.expectEqual(24869388, similarity(left, right));
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}
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fn distance(left: [1000]i32, right: [1000]i32) u32 {
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var total_distance: u32 = 0;
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for (left, right) |l, r| {
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total_distance += @abs(r - l);
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}
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return total_distance;
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}
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fn similarity(left: [1000]i32, right: [1000]i32) !i32 {
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// Make a map with value -> occurence
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var buff: [1024 * 100]u8 = undefined;
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var fbuf = std.heap.FixedBufferAllocator.init(&buff);
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const allocator = fbuf.allocator();
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var map = std.AutoHashMap(i32, u8).init(allocator);
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defer map.deinit();
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for (right) |r| {
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if (map.get(r)) |r_count| {
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try map.put(r, r_count + 1);
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} else {
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try map.put(r, 1);
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}
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}
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var total_similarity: i32 = 0;
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for (left) |l| {
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if (map.get(l)) |r_count| total_similarity += l * r_count;
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}
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return total_similarity;
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}
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