126 lines
3.3 KiB
Zig
126 lines
3.3 KiB
Zig
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const std = @import("std");
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const print = std.debug.print;
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const PairMap = struct {
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map: std.AutoHashMap(u16, u64),
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alloc: *std.mem.Allocator,
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fn squash(pair: []const u8) u16 {
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return @intCast(u16, pair[0]) << 8 | pair[1];
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}
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fn init(alloc: *std.mem.Allocator) PairMap {
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return PairMap{
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.map = std.AutoHashMap(u16, u64).init(alloc),
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.alloc = alloc,
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};
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}
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fn deinit(self: *PairMap) void {
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self.map.deinit();
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}
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fn get(self: *PairMap, pair: []const u8) u64 {
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return self.map.get(squash(pair)) orelse 0;
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}
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fn add(self: *PairMap, pair: []const u8, value: u64) void {
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self.map.put(squash(pair), self.get(pair) + value) catch {};
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}
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fn result(self: *PairMap) u64 {
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var counts = std.AutoHashMap(u8, u64).init(self.alloc);
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defer counts.deinit();
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var keys = self.map.iterator();
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while (keys.next()) |entry| {
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var key = entry.key_ptr.*;
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var value = entry.value_ptr.*;
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var left = @intCast(u8, (key & 0xff00) >> 8);
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var right = @intCast(u8, key & 0xff);
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counts.put(left, (counts.get(left) orelse 0) + value) catch {};
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counts.put(right, (counts.get(right) orelse 0) + value) catch {};
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}
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var min: u64 = std.math.maxInt(u64);
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var max: u64 = 0;
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var it = counts.valueIterator();
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while (it.next()) |value| {
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var actual = @divFloor(value.* + 1, 2);
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min = std.math.min(min, actual);
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max = std.math.max(max, actual);
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}
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return max - min;
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}
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};
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pub fn main() !void {
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var alloc = std.heap.GeneralPurposeAllocator(.{}){};
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defer std.debug.assert(!alloc.deinit());
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var gpa = &alloc.allocator;
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const stdin = std.io.getStdIn().reader();
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var res: u32 = 0;
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var mapping = std.StringHashMap(u8).init(gpa);
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defer mapping.deinit();
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defer {
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var it = mapping.keyIterator();
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while (it.next()) |key| {
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gpa.free(key.*);
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}
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}
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var pairs = PairMap.init(gpa);
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defer pairs.deinit();
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var tmp: [256]u8 = undefined;
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var maybe_polymer = try stdin.readUntilDelimiterOrEof(&tmp, '\n');
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if (maybe_polymer) |polymer| {
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var i: u32 = 0;
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while (i < polymer.len - 1) : (i += 1) {
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var pair = polymer[i..i+2];
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pairs.add(pair, 1);
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}
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}
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try stdin.skipBytes(1, .{});
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while (try stdin.readUntilDelimiterOrEof(&tmp, '\n')) |line| {
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var key = try gpa.alloc(u8, 2);
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std.mem.copy(u8, key, line[0..2]);
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try mapping.put(key, line[6]);
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}
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var step: u32 = 0;
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while (step < 40) : (step += 1) {
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var newPairs = PairMap.init(gpa);
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defer {
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pairs.deinit();
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pairs = newPairs;
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}
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var it = mapping.iterator();
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while (it.next()) |entry| {
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var key = entry.key_ptr.*;
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var insert = entry.value_ptr.*;
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var current = pairs.get(key);
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tmp[0] = key[0];
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tmp[1] = insert;
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tmp[2] = key[1];
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var left = tmp[0..2];
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var right = tmp[1..3];
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newPairs.add(left, current);
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newPairs.add(right, current);
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}
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if (step == 10) print("{}\n", .{pairs.result()});
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}
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print("{}\n", .{pairs.result()});
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}
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