Day 1 of AdventOfCode

AdventOfCode2018/1stDay/challenge2/challenge.txt

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+--- Part Two ---
+You notice that the device repeats the same frequency change list over and over. To calibrate the device, you need to find the first frequency it reaches twice.
+
+For example, using the same list of changes above, the device would loop as follows:
+
+Current frequency  0, change of +1; resulting frequency  1.
+Current frequency  1, change of -2; resulting frequency -1.
+Current frequency -1, change of +3; resulting frequency  2.
+Current frequency  2, change of +1; resulting frequency  3.
+(At this point, the device continues from the start of the list.)
+Current frequency  3, change of +1; resulting frequency  4.
+Current frequency  4, change of -2; resulting frequency  2, which has already been seen.
+In this example, the first frequency reached twice is 2. Note that your device might need to repeat its list of frequency changes many times before a duplicate frequency is found, and that duplicates might be found while in the middle of processing the list.
+
+Here are other examples:
+
++1, -1 first reaches 0 twice.
++3, +3, +4, -2, -4 first reaches 10 twice.
+-6, +3, +8, +5, -6 first reaches 5 twice.
++7, +7, -2, -7, -4 first reaches 14 twice.
+What is the first frequency your device reaches twice?

AdventOfCode2018/1stDay/challenge2/index.js

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+const fs = require('fs');
+let input = fs.readFileSync('input.txt')
+                .toString()
+                .split('\n')
+                .map((x) => parseInt(x));
+
+let seenFrequencies = new Set([0]);
+let total = 0;
+let i = 0;
+
+while (true) {
+    if (i === input.length) {
+        i = 0;
+        continue;
+    }
+    total += input[i];
+    if (seenFrequencies.has(total)) {
+        break;
+    }
+    seenFrequencies.add(total);
+    i++;
+}
+
+console.log(total)