Add day 25 solution

js/day25.js

@@ -0,0 +1,107 @@
+const { readFromFile, printSolution } = require('./utility')
+const flags = require('flags')
+const _ = require('lodash')
+const solve = (sample) => {
+    const inputs = readFromFile(25, sample).split("\n")
+
+    let map = {
+        right: {},
+        down: {}
+    }
+    const maxX = inputs[0].length
+    const maxY = inputs.length
+    for (let y = 0; y < maxY; y++) {
+        for (let x = 0; x < maxX; x++) {
+            let c = inputs[y][x]
+            let direction = ""
+            let key = createKey(x, y)
+            if (c === "v") {
+                direction = "down"
+            } else if (c === ">") {
+                direction = "right"
+            } else {
+                continue
+            }
+
+            map[direction][key] = true
+        }
+    }
+
+    let done = true
+    let iter = 0
+    while (true) {
+        done = true
+        iter++
+
+        let copy = _.cloneDeep(map)
+        for (let key of Object.keys(map.right)) {
+            let [x, y] = splitKey(key)
+            x++
+            if (x + 1 > maxX) {
+                x = 0
+            }
+
+            let newKey = createKey(x, y)
+            if (map.right[newKey] === undefined && map.down[newKey] === undefined) {
+                copy.right[newKey] = true
+                delete copy.right[key]
+                done = false
+            }
+        }
+
+        map = copy
+        copy = _.cloneDeep(map)
+
+        for (let key of Object.keys(map.down)) {
+            let [x, y] = splitKey(key)
+            y++
+            if (y + 1 > maxY) {
+                y = 0
+            }
+
+            let newKey = createKey(x, y)
+            if (map.right[newKey] === undefined && map.down[newKey] === undefined) {
+                copy.down[newKey] = true
+                delete copy.down[key]
+                done = false
+            }
+        }
+        map = copy
+
+        if (done) {
+            break
+        }
+    }
+    printMap(map, maxX, maxY)
+    printSolution(iter)
+}
+
+let printMap = (map, maxX, maxY) => {
+    let str = ""
+    for (let y = 0; y < maxY; y++) {
+        for (let x = 0; x < maxX; x++) {
+            let key = createKey(x, y)
+            if (map.right[key]) {
+                str += ">"
+            } else if (map.down[key]) {
+                str += "v"
+            } else {
+                str += "."
+            }
+        }
+
+        str += "\n"
+    }
+
+    console.log(str)
+}
+
+let createKey = (...rest) => rest.join("|")
+
+let splitKey = (key) => key.split("|")
+
+flags.defineBoolean("sample", false, "run with sample")
+flags.defineBoolean("s", false, "run with sample")
+flags.parse()
+
+solve(flags.get("sample") || flags.get("s"))