chore(i8n,learn): processed translations

curriculum/challenges/espanol/10-coding-interview-prep/rosetta-code/letter-frequency.md

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+---
+id: 5e4ce2bbac708cc68c1df25f
+title: Letter frequency
+challengeType: 5
+forumTopicId: 385263
+dashedName: letter-frequency
+---
+
+# --description--
+
+Given a string, calculate the frequency of each character.
+
+All characters should be counted. This includes lower and upper case letters, digits, whitespace, special characters, or any other distinct characters.
+
+# --instructions--
+
+Write a function to count the occurrences of each character in a given string.
+
+The function should return a 2D array with each of the elements in the following form: `['char', freq]`. The character should be a string with a length of 1, and frequency is a number denoting the count.
+
+For example, given the string "ab", your function should return `[['a', 1], ['b', 1]]`.
+
+# --hints--
+
+`letterFrequency` should be a function.
+
+```js
+assert(typeof letterFrequency == 'function');
+```
+
+`letterFrequency("Not all that Mrs. Bennet, however")` should return an array.
+
+```js
+assert(Array.isArray(letterFrequency('Not all that Mrs. Bennet, however')));
+```
+
+`letterFrequency("Not all that Mrs. Bennet, however")` should return `[[" ", 5], [", ", 1], [".", 1], ["B", 1], ["M", 1], ["N", 1], ["a", 2], ["e", 4], ["h", 2], ["l", 2], ["n", 2], ["o", 2], ["r", 2], ["s", 1], ["t", 4], ["v", 1], ["w", 1]]`.
+
+```js
+assert.deepEqual(letterFrequency('Not all that Mrs. Bennet, however'), [
+  [' ', 5],
+  [',', 1],
+  ['.', 1],
+  ['B', 1],
+  ['M', 1],
+  ['N', 1],
+  ['a', 2],
+  ['e', 4],
+  ['h', 2],
+  ['l', 2],
+  ['n', 2],
+  ['o', 2],
+  ['r', 2],
+  ['s', 1],
+  ['t', 4],
+  ['v', 1],
+  ['w', 1]
+]);
+```
+
+`letterFrequency("daughters, could ask on the ")` should return `[[' ',5],[',',1],['a',2],['c',1],['d',2],['e',2],['g',1],['h',2],['k',1],['l',1],['n',1],['o',2],['r',1],['s',2],['t',2],['u',2]]`.
+
+```js
+assert.deepEqual(letterFrequency('daughters, could ask on the '), [
+  [' ', 5],
+  [',', 1],
+  ['a', 2],
+  ['c', 1],
+  ['d', 2],
+  ['e', 2],
+  ['g', 1],
+  ['h', 2],
+  ['k', 1],
+  ['l', 1],
+  ['n', 1],
+  ['o', 2],
+  ['r', 1],
+  ['s', 2],
+  ['t', 2],
+  ['u', 2]
+]);
+```
+
+`letterFrequency("husband any satisfactory description")` should return `[[" ", 3], ["a", 4], ["b", 1], ["c", 2], ["d", 2], ["e", 1], ["f", 1], ["h", 1], ["i", 3], ["n", 3], ["o", 2], ["p", 1], ["r", 2], ["s", 4], ["t", 3], ["u", 1], ["y", 2]]`.
+
+```js
+assert.deepEqual(letterFrequency('husband any satisfactory description'), [
+  [' ', 3],
+  ['a', 4],
+  ['b', 1],
+  ['c', 2],
+  ['d', 2],
+  ['e', 1],
+  ['f', 1],
+  ['h', 1],
+  ['i', 3],
+  ['n', 3],
+  ['o', 2],
+  ['p', 1],
+  ['r', 2],
+  ['s', 4],
+  ['t', 3],
+  ['u', 1],
+  ['y', 2]
+]);
+```
+
+`letterFrequency("in various ways--with barefaced")` should return `[[" ", 3], ["-", 2], ["a", 4], ["b", 1], ["c", 1], ["d", 1], ["e", 2], ["f", 1], ["h", 1], ["i", 3], ["n", 1], ["o", 1], ["r", 2], ["s", 2], ["t", 1], ["u", 1], ["v", 1], ["w", 2], ["y", 1]]`.
+
+```js
+assert.deepEqual(letterFrequency('in various ways--with barefaced'), [
+  [' ', 3],
+  ['-', 2],
+  ['a', 4],
+  ['b', 1],
+  ['c', 1],
+  ['d', 1],
+  ['e', 2],
+  ['f', 1],
+  ['h', 1],
+  ['i', 3],
+  ['n', 1],
+  ['o', 1],
+  ['r', 2],
+  ['s', 2],
+  ['t', 1],
+  ['u', 1],
+  ['v', 1],
+  ['w', 2],
+  ['y', 1]
+]);
+```
+
+`letterFrequency("distant surmises; but he eluded")` should return `[[" ", 4], ["; ", 1], ["a", 1], ["b", 1], ["d", 3], ["e", 4], ["h", 1], ["i", 2], ["l", 1], ["m", 1], ["n", 1], ["r", 1], ["s", 4], ["t", 3], ["u", 3]]`.
+
+```js
+assert.deepEqual(letterFrequency('distant surmises; but he eluded'), [
+  [' ', 4],
+  [';', 1],
+  ['a', 1],
+  ['b', 1],
+  ['d', 3],
+  ['e', 4],
+  ['h', 1],
+  ['i', 2],
+  ['l', 1],
+  ['m', 1],
+  ['n', 1],
+  ['r', 1],
+  ['s', 4],
+  ['t', 3],
+  ['u', 3]
+]);
+```
+
+`letterFrequency("last obliged to accept the second-hand,")` should return `[[" ", 5], [", ", 1], ["-", 1], ["a", 3], ["b", 1], ["c", 3], ["d", 3], ["e", 4], ["g", 1], ["h", 2], ["i", 1], ["l", 2], ["n", 2], ["o", 3], ["p", 1], ["s", 2], ["t", 4]]`.
+
+```js
+assert.deepEqual(letterFrequency('last obliged to accept the second-hand,'), [
+  [' ', 5],
+  [',', 1],
+  ['-', 1],
+  ['a', 3],
+  ['b', 1],
+  ['c', 3],
+  ['d', 3],
+  ['e', 4],
+  ['g', 1],
+  ['h', 2],
+  ['i', 1],
+  ['l', 2],
+  ['n', 2],
+  ['o', 3],
+  ['p', 1],
+  ['s', 2],
+  ['t', 4]
+]);
+```
+
+# --seed--
+
+## --seed-contents--
+
+```js
+function letterFrequency(txt) {
+
+}
+```
+
+# --solutions--
+
+```js
+function letterFrequency(txt) {
+    var cs = txt.split(''),
+        i = cs.length,
+        dct =  {},
+        c = '',
+        keys;
+
+    while (i--) {
+        c = cs[i];
+        dct[c] = (dct[c] || 0) + 1;
+    }
+
+    keys = Object.keys(dct);
+    keys.sort();
+    return keys.map(function (c) { return [c, dct[c]]; });
+}
+```