.

2021/10.js

@@ -0,0 +1,30 @@
+const opens = ["(", "[", "{", "<"]
+const closes = [")", "]", "}", ">"]
+const scores1 = { ")": 3, "]": 57, "}": 1197, ">": 25137 }
+const scores2 = { ")": 1, "]": 2, "}": 3, ">": 4 }
+
+function parse(str) {
+    let stack = []
+
+    for (let i = 0; i < str.length; i++) {
+        let char = str[i]
+
+        if (opens.includes(char)) {
+            stack.push(closes[opens.indexOf(char)])
+        } else if (char != stack.pop()) {
+            return scores1[char]
+        }
+    }
+
+    return stack.reverse()
+}
+
+function day10(input, part2) {
+    let results = input.split("\n").map(parse)
+
+    if (!part2) {
+        return results.filter((e) => !Array.isArray(e)).sum()
+    } else {
+        return results.filter((e) => Array.isArray(e)).map((e) => e.reduce((a, b) => a * 5 + scores2[b], 0)).medianNumeric()
+    }
+}