Day 2

02/solution01.js

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+// AdventOfCode2018-02
+
+var twiceCounter = 0; 
+var thriceCounter = 0;
+
+// Import the input file
+var fs = require('fs');
+var frequency = 0; 
+
+var textFile = fs.readFileSync('./input.txt').toString();
+var textArray = textFile.split(/\r?\n/);
+
+// For each line of the input file
+textArray.forEach(line => {
+    var searchCharHistory = [];
+    var lineTwiceCounter = 0;
+    var lineThriceCounter = 0;
+    for (i = 0; i < line.length; i++) {
+        searchChar = line.charAt(i);
+        if (!searchCharHistory.indexOf(searchChar) >= 0) {
+            // If we haven't already counted this letter 
+            //console.log('Searching for ' + searchChar + ' in line ' + line);
+            var re = new RegExp(searchChar, 'g');
+            var matchCharCount = (line.match(re) || []).length;
+            //console.log(matchCharCount);
+            // Check if a letter appears twice (and increment the counter) 
+            if (matchCharCount == 2) {
+                lineTwiceCounter += 1;
+            }
+            // Check if a letter appears three times (and increment the counter)
+            else if (matchCharCount == 3) {
+                lineThriceCounter += 1;
+            }
+        }
+        searchCharHistory.push(searchChar);
+    }
+    if (lineTwiceCounter > 0) {
+        twiceCounter += 1;
+    }
+    if (lineThriceCounter > 0) {
+        thriceCounter += 1;
+    }
+});
+
+console.log(twiceCounter);
+console.log(thriceCounter);
+// multiply the two counters together 
+console.log('The checksum is ' + (twiceCounter * thriceCounter));