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Implemented 'Find First Palindromic String in the Array' challenge
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LeetCode/LeetCode/Challenges/FindFirstPalindromicStringInTheArray.swift
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| Original file line number | Diff line number | Diff line change |
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| // | ||
| // FindFirstPalindromicStringInTheArray.swift | ||
| // LeetCode | ||
| // | ||
| // Created by William Boles on 06/03/2024. | ||
| // | ||
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| import Foundation | ||
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| //https://leetcode.com/problems/find-first-palindromic-string-in-the-array/ | ||
| struct FindFirstPalindromicStringInTheArray { | ||
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| //Time: O(n * m) where n is the number of elements in `words` | ||
| // where m is the largest element in `words` | ||
| //Space: O(1) | ||
| //array | ||
| //two pointers | ||
| // | ||
| //Solution Description: | ||
| //Taking each element in `words`, we use two pointers starting at either end of `word`. We compare the element at each pointer, | ||
| //if they match we increment and decrement to move onto the next elements and repeat the process; if they don't matchwe know | ||
| //that this `word` is not a palindrome and can stop comparing elements. We reapt this process with each `word` until we find a | ||
| //palindrome, which we immediately return. If after iterating through all elements in `words` we don't find a palindrome we | ||
| //return an empty string. | ||
| func firstPalindrome(_ words: [String]) -> String { | ||
| for word in words { | ||
| let characters = Array(word) | ||
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| var left = 0 | ||
| var right = characters.count - 1 | ||
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| var isPalindrome = true | ||
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| while left < right { | ||
| if characters[left] != characters[right] { | ||
| isPalindrome = false | ||
| break | ||
| } | ||
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| left += 1 | ||
| right -= 1 | ||
| } | ||
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| if isPalindrome { | ||
| return word | ||
| } | ||
| } | ||
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| return "" | ||
| } | ||
| } |
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LeetCode/LeetCodeTests/Tests/FindFirstPalindromicStringInTheArrayTests.swift
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,39 @@ | ||
| // | ||
| // FindFirstPalindromicStringInTheArrayTests.swift | ||
| // LeetCodeTests | ||
| // | ||
| // Created by William Boles on 06/03/2024. | ||
| // | ||
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| import XCTest | ||
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| @testable import LeetCode | ||
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| final class FindFirstPalindromicStringInTheArrayTests: XCTestCase { | ||
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| // MARK: - Tests | ||
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| func test_A() { | ||
| let words = ["abc","car","ada","racecar","cool"] | ||
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| let result = FindFirstPalindromicStringInTheArray().firstPalindrome(words) | ||
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| XCTAssertEqual(result, "ada") | ||
| } | ||
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| func test_B() { | ||
| let words = ["notapalindrome","racecar"] | ||
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| let result = FindFirstPalindromicStringInTheArray().firstPalindrome(words) | ||
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| XCTAssertEqual(result, "racecar") | ||
| } | ||
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| func test_C() { | ||
| let words = ["def","ghi"] | ||
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| let result = FindFirstPalindromicStringInTheArray().firstPalindrome(words) | ||
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| XCTAssertEqual(result, "") | ||
| } | ||
| } |