2020 day 7

2020/07/part2.js

@@ -0,0 +1,30 @@
+const fs = require('fs');
+
+const data = fs.readFileSync('input.txt', 'utf-8');
+const rules = data.split('\n');
+
+
+let bagRules = {}
+rules.forEach(rule => {
+  halves = rule.split(' bags contain ')
+  bagRules[halves[0]] =
+    halves[1].replace(/( bags| bag|\.)/g, "")
+      .split(", ")
+      .map((t)=>{
+        return {
+          name: t.replace(/\d /,""),
+          amt: t[0]
+        }
+      })
+});
+
+function howManyIn(name) {
+  let amt = 1
+  bagRules[name].forEach(rule => {
+    if (rule.amt == 'n') {return}
+    amt += parseInt(rule.amt) * howManyIn(rule.name)
+  })
+  return amt
+}
+
+howManyIn('shiny gold')-1 // subtract the first gold bag