Code/README fixes for the "Palindrome Check".

This commit is contained in:
Oleksii Trekhleb 2022-01-23 21:47:57 +01:00
parent ea28788ed8
commit 90addf9b18
6 changed files with 48 additions and 41 deletions

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@ -102,7 +102,7 @@ a set of rules that precisely define a sequence of operations.
* `A` [Combination Sum](src/algorithms/sets/combination-sum) - find all combinations that form specific sum * `A` [Combination Sum](src/algorithms/sets/combination-sum) - find all combinations that form specific sum
* **Strings** * **Strings**
* `B` [Hamming Distance](src/algorithms/string/hamming-distance) - number of positions at which the symbols are different * `B` [Hamming Distance](src/algorithms/string/hamming-distance) - number of positions at which the symbols are different
* `B` [Palindrome Check](src/algorithms/string/palindrome-check) - is the string the same in reverse * `B` [Palindrome](src/algorithms/string/palindrome) - check if the string is the same in reverse
* `A` [Levenshtein Distance](src/algorithms/string/levenshtein-distance) - minimum edit distance between two sequences * `A` [Levenshtein Distance](src/algorithms/string/levenshtein-distance) - minimum edit distance between two sequences
* `A` [KnuthMorrisPratt Algorithm](src/algorithms/string/knuth-morris-pratt) (KMP Algorithm) - substring search (pattern matching) * `A` [KnuthMorrisPratt Algorithm](src/algorithms/string/knuth-morris-pratt) (KMP Algorithm) - substring search (pattern matching)
* `A` [Z Algorithm](src/algorithms/string/z-algorithm) - substring search (pattern matching) * `A` [Z Algorithm](src/algorithms/string/z-algorithm) - substring search (pattern matching)

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@ -1,25 +0,0 @@
# Palindrome Check
A Palindrome is a string that reads the same forwards and backwards.
This means that the second half of the string is the reverse of the
first half.
## Examples
The following are palindromes (thus would return TRUE):
- "a"
- "pop" -> p + o + p
- "deed" -> de + ed
- "kayak" -> ka + y + ak
- "racecar" -> rac + e + car
The following are NOT palindromes (thus would return FALSE):
- "rad"
- "dodo"
- "polo"
## References
[GeeksforGeeks - Check if a number is Palindrome](https://www.geeksforgeeks.org/check-if-a-number-is-palindrome/)

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@ -1,14 +0,0 @@
import palindromeCheck from '../palindromeCheck';
describe('palindromeCheck', () => {
it('should return whether or not the string is a palindrome', () => {
expect(palindromeCheck('a')).toBe(true);
expect(palindromeCheck('pop')).toBe(true);
expect(palindromeCheck('deed')).toBe(true);
expect(palindromeCheck('kayak')).toBe(true);
expect(palindromeCheck('racecar')).toBe(true);
expect(palindromeCheck('rad')).toBe(false);
expect(palindromeCheck('dodo')).toBe(false);
expect(palindromeCheck('polo')).toBe(false);
});
});

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@ -0,0 +1,29 @@
# Palindrome Check
A [Palindrome](https://en.wikipedia.org/wiki/Palindrome) is a string that reads the same forwards and backwards.
This means that the second half of the string is the reverse of the
first half.
## Examples
The following are palindromes (thus would return `TRUE`):
```
- "a"
- "pop" -> p + o + p
- "deed" -> de + ed
- "kayak" -> ka + y + ak
- "racecar" -> rac + e + car
```
The following are NOT palindromes (thus would return `FALSE`):
```
- "rad"
- "dodo"
- "polo"
```
## References
- [GeeksForGeeks - Check if a number is Palindrome](https://www.geeksforgeeks.org/check-if-a-number-is-palindrome/)

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@ -0,0 +1,15 @@
import isPalindrome from '../isPalindrome';
describe('palindromeCheck', () => {
it('should return whether or not the string is a palindrome', () => {
expect(isPalindrome('a')).toBe(true);
expect(isPalindrome('pop')).toBe(true);
expect(isPalindrome('deed')).toBe(true);
expect(isPalindrome('kayak')).toBe(true);
expect(isPalindrome('racecar')).toBe(true);
expect(isPalindrome('rad')).toBe(false);
expect(isPalindrome('dodo')).toBe(false);
expect(isPalindrome('polo')).toBe(false);
});
});

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@ -3,9 +3,10 @@
* @return {boolean} * @return {boolean}
*/ */
export default function palindromeCheck(string) { export default function isPalindrome(string) {
let left = 0; let left = 0;
let right = string.length - 1; let right = string.length - 1;
while (left < right) { while (left < right) {
if (string[left] !== string[right]) { if (string[left] !== string[right]) {
return false; return false;
@ -13,5 +14,6 @@ export default function palindromeCheck(string) {
left += 1; left += 1;
right -= 1; right -= 1;
} }
return true; return true;
} }