Working part 2

Not 100% sure if my assumption at the end to count coords "surrounded"
by the area is sound. Is it possible to have a coord on the "edge" of
the area? Then it'd still be part of the area, but not be surrounded.

Oh well, the answer works in this case.

Author: romellem

6/part-two.js

@@ -1,7 +1,65 @@
 const fs = require('fs');
 const path = require('path');
+const distance = require('manhattan');
+const flat = require('array.prototype.flat');
 
 let raw_input = fs.readFileSync(path.resolve(__dirname, './input.txt'), 'utf8');
 
 // Last filter is to remove any empty lines
-let input = raw_input.split('\n').filter(n => n)[0];
+let input = raw_input.split('\n').filter(n => n);
+
+let coordinates = input.map(p => p.split(',').map(n => +n));
+
+let flattened = flat(coordinates);
+let largest = Math.max.apply(null, flattened);
+
+let grid = Array(largest + 2)
+    .fill()
+    .map(n => {
+        return Array(largest + 2).fill(-1);
+    });
+
+// Loop through grid and mark spots that are coordinates
+coordinates.forEach((coord, index) => {
+    let [i, j] = coord;
+    grid[i][j] = 'C' + index;
+});
+
+const MIN_DIST = 10000;
+
+let min_dist_count = 0;
+for (let i = 0; i < grid.length; i++) {
+    let row = grid[i];
+    for (let j = 0; j < grid.length; j++) {
+        let cell = row[j];
+        if (typeof cell !== 'string') {
+            // Not a coord, measure it
+            let lengths = coordinates.map((coord, index) => {
+                return distance(coord, [i, j]);
+            });
+
+            let sum = lengths.reduce((a, b) => a + b);
+            if (sum < MIN_DIST) {
+                grid[i][j] = 'close';
+                min_dist_count++;
+            }
+        }
+    }
+}
+
+// Loop through coords, and find ones that are surrounded by "found" areas
+coordinates.forEach(coord => {
+    let [i, j] = coord;
+    let t = grid[i - 1][j];
+    let r = grid[i][j + 1];
+    let b = grid[i + 1][j];
+    let l = grid[i][j - 1];
+
+    const C = 'close';
+
+    if (t === C && r === C && b === C && l === C) {
+        min_dist_count++;
+    }
+});
+
+console.log(min_dist_count);