ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
90 lines
2.5 KiB
Markdown
90 lines
2.5 KiB
Markdown
---
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id: 587d7b86367417b2b2512b3c
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title: Use Caution When Reinitializing Variables Inside a Loop
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challengeType: 1
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forumTopicId: 301194
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dashedName: use-caution-when-reinitializing-variables-inside-a-loop
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---
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# --description--
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Sometimes it's necessary to save information, increment counters, or re-set variables within a loop. A potential issue is when variables either should be reinitialized, and aren't, or vice versa. This is particularly dangerous if you accidentally reset the variable being used for the terminal condition, causing an infinite loop.
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Printing variable values with each cycle of your loop by using `console.log()` can uncover buggy behavior related to resetting, or failing to reset a variable.
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# --instructions--
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The following function is supposed to create a two-dimensional array with `m` rows and `n` columns of zeroes. Unfortunately, it's not producing the expected output because the `row` variable isn't being reinitialized (set back to an empty array) in the outer loop. Fix the code so it returns a correct 3x2 array of zeroes, which looks like `[[0, 0], [0, 0], [0, 0]]`.
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# --hints--
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Your code should set the `matrix` variable to an array holding 3 rows of 2 columns of zeroes each.
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```js
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assert(JSON.stringify(matrix) == '[[0,0],[0,0],[0,0]]');
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```
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The `matrix` variable should have 3 rows.
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```js
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assert(matrix.length == 3);
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```
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The `matrix` variable should have 2 columns in each row.
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```js
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assert(
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matrix[0].length == 2 && matrix[1].length === 2 && matrix[2].length === 2
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);
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```
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# --seed--
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## --seed-contents--
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```js
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function zeroArray(m, n) {
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// Creates a 2-D array with m rows and n columns of zeroes
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let newArray = [];
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let row = [];
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for (let i = 0; i < m; i++) {
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// Adds the m-th row into newArray
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for (let j = 0; j < n; j++) {
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// Pushes n zeroes into the current row to create the columns
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row.push(0);
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}
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// Pushes the current row, which now has n zeroes in it, to the array
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newArray.push(row);
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}
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return newArray;
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}
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let matrix = zeroArray(3, 2);
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console.log(matrix);
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```
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# --solutions--
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```js
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function zeroArray(m, n) {
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// Creates a 2-D array with m rows and n columns of zeroes
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let newArray = [];
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for (let i = 0; i < m; i++) {
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let row = [];
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// Adds the m-th row into newArray
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for (let j = 0; j < n; j++) {
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// Pushes n zeroes into the current row to create the columns
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row.push(0);
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}
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// Pushes the current row, which now has n zeroes in it, to the array
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newArray.push(row);
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}
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return newArray;
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}
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let matrix = zeroArray(3, 2);
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console.log(matrix);
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```
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