.

2021/5.js

@@ -0,0 +1,31 @@
+function day5(input, part2) {
+    let lines = input.split("\n").map((e) => e.split(" -> ").map((e) => new Point(...e.split(",").num())))
+
+    if (!part2) {
+        lines = lines.filter((e) => e[0].x == e[1].x || e[0].y == e[1].y)
+    }
+
+    let dict = {}
+
+    for (let line of lines) {
+        let xrange = utils.signAgnosticInclusiveRange(line[0].x, line[1].x)
+        let yrange = utils.signAgnosticInclusiveRange(line[0].y, line[1].y)
+
+        if (xrange.length == 1) {
+            xrange = yrange.map(() => line[0].x)
+        }
+
+        if (yrange.length == 1) {
+            yrange = xrange.map(() => line[0].y)
+        }
+
+        for (let i = 0; i < xrange.length; i++) {
+            let x = xrange[i]
+            let y = yrange[i]
+
+            dict[[x, y]] = (dict[[x, y]] || 0) + 1
+        }
+    }
+
+    return Object.values(dict).filter((e) => e > 1).length
+}