2020 day 13

2020/13/part1.js

@@ -0,0 +1,21 @@
+// this was fairly simple; just keep increasing the wait until you find a bus that leaves. there is probably a more efficient solution but this works
+const fs = require('fs');
+const input = fs.readFileSync('input.txt', 'utf-8').split('\n');
+const time = Number(input[0]);
+const busses = input[1].split(',').filter(v=>v!='x').map(n => Number(n));
+
+let isBus = false;
+let timeDif = 0;
+let busID;
+for (; !isBus; timeDif++) {
+  for(bus of busses) {
+    if ((time + timeDif) % bus == 0){
+      busID = bus;
+      isBus = true;
+      break;
+    }
+  }
+}
+// the for loop does an extra increment at the end oops
+timeDif--
+console.log(timeDif*busID)