Implemented suggesting improvements

snippets/stringPermutations.md

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+### stringPermutations
+
+⚠️ **WARNING**: This function's execution time increases exponentially with each character. Anything more than 8 to 10 characters will cause your browser to hang as it tries to solve all the different combinations.
+
+Generates all permutations of a string (contains duplicates).
+
+Use recursion.
+For each letter in the given string, create all the partial permutations for the rest of its letters.
+Use `Array.map()` to combine the letter with each partial permutation, then `Array.reduce()` to combine all permutations in one array.
+Base cases are for string `length` equal to `2` or `1`.
+
+```js
+const stringPermutations = str => {
+  if (str.length <= 2) return str.length === 2 ? [str, str[1] + str[0]] : [str];
+  return str
+    .split('')
+    .reduce(
+      (acc, letter, i) =>
+        acc.concat(stringPermutations(str.slice(0, i) + str.slice(i + 1)).map(val => letter + val)),
+      []
+    );
+};
+```
+
+```js
+stringPermutations('abc'); // ['abc','acb','bac','bca','cab','cba']
+```