Day 3 js

R/.Rproj.user/shared/notebooks/paths

@@ -10,4 +10,5 @@
 /Users/hrbrmstr/Development/2020-code-advent/input/03-01.txt="3353A6D2"
 /Users/hrbrmstr/Development/2020-code-advent/js/01.js="77D3BDB6"
 /Users/hrbrmstr/Development/2020-code-advent/js/02.js="BC8B36A1"
+/Users/hrbrmstr/Development/2020-code-advent/js/03.js="E24752E6"
 /private/tmp/test.txt="DFC19AA4"

js/03.js

@@ -0,0 +1,54 @@
+var fs = require("fs")
+
+orig_map = fs.readFileSync("../input/03-01.txt", "utf-8")
+  .split("\n")
+  .filter((line) => line != '')
+
+count_trees = function(orig_map, slope_x, slope_y) {
+
+  m_cols = orig_map[0].length
+  m_rows = orig_map.length
+
+  n_tiles = Math.floor((slope_x+1) * m_rows / (m_cols))
+
+  actual_map = orig_map.map((row) => {
+    return(row.repeat(n_tiles))
+  })
+
+  xpos = 0
+  ypos = 0
+  n_trees = 0
+
+  while(true) {
+
+    xpos = xpos + slope_x
+    ypos = ypos + slope_y
+
+    if (ypos >= m_rows) break
+
+    if (actual_map[ypos][xpos] == "#") n_trees = n_trees + 1
+
+  }
+
+  return(n_trees)
+
+
+}
+
+// 03-01
+
+console.log(count_trees(orig_map, 3, 1))
+
+// 03-02
+
+x = [ 1, 3, 5, 7, 1 ]
+y = [ 1, 1, 1, 1, 2 ]
+
+console.log(
+  [...Array(x.length).keys()]
+    .map((idx) => count_trees(orig_map, x[idx], y[idx]))
+    .reduce((a, b) => a * b)
+)
+
+
+