Day 19

day19/part1.js

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+module.exports = input => {
+  let [workflows, parts] = input.split(/\r?\n\r?\n/)
+    .map(g => g.split(/\r?\n/));
+
+  workflows = workflows.map(w => w.match(/(\w+)\{(.*)\}/))
+    .map(([_, id, w]) => [id, w.split(',')])
+    .reduce((map, [id, w]) => map.set(id, w), new Map());
+
+  const eval = (id, values) => {
+    if (id == 'A') {
+      return true;
+    }
+    if (id == 'R') {
+      return false;
+    }
+
+    let rules = workflows.get(id);
+    for (let rule of rules) {
+      if (rule.indexOf(':') >= 0) {
+        let [condition, result] = rule.split(':');
+        let [_, rating, comparison, value] = condition.match(/(\w)([<>])(\d+)/);
+        let testee = values['xmas'.indexOf(rating)];
+        value = Number(value);
+        if ((comparison == '>' && testee > value)
+          || (comparison == '<' && testee < value)) {
+          return eval(result, values);
+        }
+      } else {
+        return eval(rule, values);
+      }
+    }
+  }
+
+  parts = parts.map(p => p.slice(1, p.length - 1))
+    .map(p => p.split(',').map(r => Number(r.split('=')[1])));
+
+  return parts.filter(p => eval('in', p))
+    .map(([x, m, a, s]) => x + m + a + s)
+    .reduce((a, b) => a + b);
+}

day19/part2.js

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+function range(r1, r2) {
+  return r1 > r2 ? [] : [r1, r2];
+}
+
+function split([r1, r2], comparison, value) {
+  if (comparison == '>') {
+    return [range(Math.max(value + 1, r1), r2), range(r1, Math.min(r2, value))];
+  } else {
+    return [range(r1, Math.min(value - 1, r2)), range(Math.max(value, r1), r2)];
+  }
+}
+
+module.exports = input => {
+  let [workflows, _] = input.split(/\r?\n\r?\n/)
+    .map(g => g.split(/\r?\n/));
+
+  workflows = workflows.map(w => w.match(/(\w+)\{(.*)\}/))
+    .map(([_, id, w]) => [id, w.split(',')])
+    .reduce((map, [id, w]) => map.set(id, w), new Map());
+
+  const eval = (id, ranges) => {
+    if (id == 'A') {
+      return [ranges];
+    }
+    if (id == 'R') {
+      return [[], [], [], []];
+    }
+
+    let rules = workflows.get(id);
+    let results = [];
+
+    for (let rule of rules) {
+      if (rule.indexOf(':') >= 0) {
+        let [condition, result] = rule.split(':');
+        let [_, rating, comparison, value] = condition.match(/(\w)([<>])(\d+)/);
+        let index = 'xmas'.indexOf(rating);
+        let testRange = ranges[index];
+        value = Number(value);
+
+        let [positive, negative] = split(testRange, comparison, value);
+
+        if (positive.length) {
+          let nranges = [...ranges];
+          nranges.splice(index, 1, positive);
+          results.push(...eval(result, nranges));
+        }
+
+        if (negative.length == 0) {
+          break;
+        }
+
+        ranges = [...ranges];
+        ranges.splice(index, 1, negative)
+      }
+      else {
+        results.push(...eval(rule, ranges));
+      }
+    }
+
+    return results.filter(r => r.some(p => p.length));
+  }
+
+  return eval('in', [[1, 4000], [1, 4000], [1, 4000], [1, 4000]])
+    .map(r => r.reduce((p, [r1, r2]) => p * (r2 - r1 + 1), 1))
+    .reduce((a, b) => a + b);
+}

day19/test.js

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+const expect = require('expect.js');
+const part1 = require('./part1');
+const part2 = require('./part2');
+
+describe('Day 19: Part 1', () => {
+  it('Should sum rating number for all accepted parts', () => {
+    expect(part1(`px{a<2006:qkq,m>2090:A,rfg}
+pv{a>1716:R,A}
+lnx{m>1548:A,A}
+rfg{s<537:gd,x>2440:R,A}
+qs{s>3448:A,lnx}
+qkq{x<1416:A,crn}
+crn{x>2662:A,R}
+in{s<1351:px,qqz}
+qqz{s>2770:qs,m<1801:hdj,R}
+gd{a>3333:R,R}
+hdj{m>838:A,pv}
+
+{x=787,m=2655,a=1222,s=2876}
+{x=1679,m=44,a=2067,s=496}
+{x=2036,m=264,a=79,s=2244}
+{x=2461,m=1339,a=466,s=291}
+{x=2127,m=1623,a=2188,s=1013}`)).to.equal(19114);
+  });
+});
+describe('Day 19: Part 2', () => {
+  it('Should count how many distinct combitions of ratings will be accepted', () => {
+    expect(part2(`px{a<2006:qkq,m>2090:A,rfg}
+pv{a>1716:R,A}
+lnx{m>1548:A,A}
+rfg{s<537:gd,x>2440:R,A}
+qs{s>3448:A,lnx}
+qkq{x<1416:A,crn}
+crn{x>2662:A,R}
+in{s<1351:px,qqz}
+qqz{s>2770:qs,m<1801:hdj,R}
+gd{a>3333:R,R}
+hdj{m>838:A,pv}
+
+{x=787,m=2655,a=1222,s=2876}
+{x=1679,m=44,a=2067,s=496}
+{x=2036,m=264,a=79,s=2244}
+{x=2461,m=1339,a=466,s=291}
+{x=2127,m=1623,a=2188,s=1013}`)).to.equal(167409079868000);
+  });
+});