despair day 4

solutions/04.ts

@@ -0,0 +1,68 @@
+import { solvables } from "../main.ts";
+
+import type { Solvable } from "../solvable.ts";
+import { readInput } from "../utils.ts";
+
+class DayFour implements Solvable {
+    input = readInput('04')
+
+    public part1(): Solvable {
+
+        const transpose = (m: string[][]) => m[0].map((_,i) => m.map(x => x[i]))
+
+        const matrix = this.input.trim().split('\n').map(line => line.split(''))
+
+        const countOccHorizontal = (mat: string[][]) => mat
+            .map(line => line.join('')
+            .matchAll(/(XMAS|SAMX)/g)
+            .map(match => match[0])
+            .toArray().length)
+            .reduce((prev, curr) => prev + curr)
+
+        // b/y = height
+        // a/x = width
+        // start top right
+
+        const getDiagonals = (mat: string[][]) => {
+            let [b,a] = [0, mat[0].length - 1]
+            const lines = []
+            while (b < mat.length) {
+                let [y,x] = [b,a]
+                let line = ''
+                // walk top left of diagonal to bottom right
+                while (x < mat[y].length && y < mat.length - 1) {
+                    line += mat[y][x]
+                    y++
+                    x++
+                }
+                lines.push(line.split(''))
+
+                if (a > 0) {
+                    a--
+                } else {
+                    b++
+                }
+            }
+            return lines
+        }
+
+        // console.log(getDiagonals(matrix.reverse()))
+
+        console.log(transpose(matrix).map(line=> line.join('')))
+
+        const downRight = countOccHorizontal(getDiagonals(matrix))
+        const downLeft = countOccHorizontal(getDiagonals(matrix.reverse()))
+        const horizontal = countOccHorizontal(matrix)
+        const vertical = countOccHorizontal(transpose(matrix))
+
+        console.log(horizontal + vertical + downRight + downLeft)
+        
+        return this
+    }
+
+    public part2(): Solvable {
+        return this
+    }
+}
+
+solvables.push(new DayFour())