-
Notifications
You must be signed in to change notification settings - Fork 10
/
Day14.cs
118 lines (93 loc) · 3.93 KB
/
Day14.cs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
using AdventOfCode.CSharp.Common;
using System;
namespace AdventOfCode.CSharp.Y2021.Solvers;
public class Day14 : ISolver
{
public static void Solve(ReadOnlySpan<byte> input, Solution solution)
{
// Stores the counts of each pair in the polymer.
// Pairs are represented by (pair[0] - 'A') * 26 + (pair[1] - 'A');
Span<long> pairCounts = stackalloc long[26 * 26];
// Parse the polymer template
int startingElement = input[0] - 'A';
int prevElement = startingElement;
int i = 1;
byte c;
while ((c = input[i++]) != '\n')
{
int element = c - 'A';
pairCounts[prevElement * 26 + element]++;
prevElement = element;
}
// Given the pair as the key, returns the two pairs that get created as a result
// The two pairs appear in the top and bottom 16 bits of the integer value