50 lines
1.4 KiB
D
50 lines
1.4 KiB
D
module day_1.solution;
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import std.file;
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import std.string : splitLines;
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import std.algorithm;
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import std.stdio;
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import std.uni : isNumber;
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import std.functional;
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/// Parses the first and last digits, using a function F to determine if and
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/// what digit is at a string at a particular index. F should return -1 if no
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/// digit exists.
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int parseDigits(int delegate(string, size_t) F)(string s) {
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int a = -1, b = -1;
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for (size_t i = 0; i < s.length; i++) {
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int an = F(s, i);
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int bn = F(s, s.length-i-1);
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if (a == -1 && an != -1) a = an;
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if (b == -1 && bn != -1) b = bn;
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if (a != -1 && b != -1) break;
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}
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return a * 10 + b;
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}
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void part1() {
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readText("part_1_input.txt").splitLines()
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.map!(line => parseDigits!((s, i) => isNumber(s[i]) ? s[i] - '0' : -1)(line))
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.sum().writeln();
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}
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void part2() {
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int findDigit(string s, size_t idx) {
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if (isNumber(s[idx])) return s[idx] - '0';
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const string[] words = ["one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];
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static foreach (size_t i, string word; words) {
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if (s.length - idx >= word.length && s[idx .. idx + word.length] == word) return cast(int) i + 1;
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}
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return -1;
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}
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readText("part_2_input.txt").splitLines()
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.map!(line => parseDigits!((s, i) => findDigit(s, i))(line))
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.sum().writeln();
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}
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void main() {
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part1();
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part2();
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}
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