Add 4 array snippets

snippets/ranking.md

@@ -0,0 +1,23 @@
+---
+title: Array ranking
+tags: array,math
+expertise: intermediate
+author: chalarangelo
+firstSeen: 2022-04-13T05:00:00-04:00
+---
+
+Calculates the ranking of an array based on a comparator function.
+
+- Use `Array.prototype.map()` and `Array.prototype.filter()` to map each element to a rank using the provided comparator function.
+
+```js
+const ranking = (arr, compFn) =>
+  arr.map(a => arr.filter(b => compFn(a, b)).length + 1);
+```
+
+```js
+ranking([8, 6, 9, 5], (a, b) => a < b);
+// [2, 3, 1, 4]
+ranking(['c', 'a', 'b', 'd'], (a, b) => a.localeCompare(b) > 0);
+// [3, 1, 2, 4]
+```