86 lines
2.5 KiB
D
86 lines
2.5 KiB
D
import std.stdio;
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import std.file;
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import std.string;
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import std.algorithm;
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import std.array;
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import std.ascii : isDigit;
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import std.conv;
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struct Point {const int x, y;}
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char getChar(ref char[][] array, int x, int y) {
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if (y >= 0 && y < array.length && x >= 0 && x < array[y].length) return array[y][x];
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return '.';
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}
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void part1() {
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char[][] schematic = File("input.txt").byLineCopy()
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.map!(line => cast(char[])line)
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.array();
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bool hasAdjacentSymbol(int x, int y, int length) {
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for (int i = y-1; i < y+2; i++) {
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for (int j = x-1; j < x+length+1; j++) {
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const char c = getChar(schematic, j, i);
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if (c != '.' && !isDigit(c)) return true;
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}
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}
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return false;
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}
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int sum = 0;
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for (int y = 0; y < schematic.length; y++) {
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for (int x = 0; x < schematic[y].length; x++) {
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if (isDigit(schematic[y][x])) {
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int length = 1;
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while (x + length < schematic[y].length && isDigit(schematic[y][x+length])) length++;
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if (hasAdjacentSymbol(x, y, length)) {
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int n = schematic[y][x..x+length].to!int;
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sum += n;
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}
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x += length;
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}
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}
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}
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writeln(sum);
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}
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void part2() {
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char[][] schematic = File("input.txt").byLineCopy()
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.map!(line => cast(char[])line)
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.array();
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Point[] findGears(int x, int y, int length) {
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Point[] gears;
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for (int i = y-1; i < y+2; i++) {
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for (int j = x-1; j < x+length+1; j++) {
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if (getChar(schematic, j, i) == '*') gears ~= Point(j, i);
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}
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}
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return gears;
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}
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int[][Point] gearNumbers;
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for (int y = 0; y < schematic.length; y++) {
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for (int x = 0; x < schematic[y].length; x++) {
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if (isDigit(schematic[y][x])) {
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int length = 1;
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while (x + length < schematic[y].length && isDigit(schematic[y][x+length])) length++;
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int n = schematic[y][x..x+length].to!int;
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Point[] gears = findGears(x, y, length);
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foreach (Point gear; gears) {
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if (gear !in gearNumbers) gearNumbers[gear] = [];
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gearNumbers[gear] ~= n;
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}
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x += length;
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}
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}
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}
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gearNumbers.values.map!(a => a.length == 2 ? a[0] * a[1] : 0).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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