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Formatted question description: https://leetcode.ca/all/2108.html

2108. Find First Palindromic String in the Array (Easy)

Given an array of strings words, return the first palindromic string in the array. If there is no such string, return an empty string "".

A string is palindromic if it reads the same forward and backward.

 

Example 1:

Input: words = ["abc","car","ada","racecar","cool"]
Output: "ada"
Explanation: The first string that is palindromic is "ada".
Note that "racecar" is also palindromic, but it is not the first.

Example 2:

Input: words = ["notapalindrome","racecar"]
Output: "racecar"
Explanation: The first and only string that is palindromic is "racecar".

Example 3:

Input: words = ["def","ghi"]
Output: ""
Explanation: There are no palindromic strings, so the empty string is returned.

 

Constraints:

  • 1 <= words.length <= 100
  • 1 <= words[i].length <= 100
  • words[i] consists only of lowercase English letters.

Similar Questions:

Solution 1.

  • // OJ: https://leetcode.com/problems/find-first-palindromic-string-in-the-array/
// Time: O(NW)
// Space: O(W)
class Solution {
public:
    string firstPalindrome(vector<string>& A) {
        for (auto &s : A) {
            string r(rbegin(s), rend(s));
            if (r == s) return s;
        }
        return "";
    }
};

  • class Solution:
    def firstPalindrome(self, words: List[str]) -> str:
        def check(s):
            i, j = 0, len(s) - 1
            while i < j:
                if s[i] != s[j]:
                    return False
                i += 1
                j -= 1
            return True

        for word in words:
            if check(word):
                return word
        return ''

############

# 2108. Find First Palindromic String in the Array
# https://leetcode.com/problems/find-first-palindromic-string-in-the-array/

class Solution:
    def firstPalindrome(self, words: List[str]) -> str:
        res = ""
        
        for x in words:
            if x == x[::-1]:
                return x
        
        return res


  • class Solution {
    public String firstPalindrome(String[] words) {
        for (var w : words) {
            boolean ok = true;
            for (int i = 0, j = w.length() - 1; i < j && ok; ++i, --j) {
                if (w.charAt(i) != w.charAt(j)) {
                    ok = false;
                }
            }
            if (ok) {
                return w;
            }
        }
        return "";
    }
}

  • func firstPalindrome(words []string) string {
	for _, w := range words {
		ok := true
		for i, j := 0, len(w)-1; i < j && ok; i, j = i+1, j-1 {
			if w[i] != w[j] {
				ok = false
			}
		}
		if ok {
			return w
		}
	}
	return ""
}

  • function firstPalindrome(words: string[]): string {
    for (const word of words) {
        let left = 0;
        let right = word.length - 1;
        while (left < right) {
            if (word[left] !== word[right]) {
                break;
            }
            left++;
            right--;
        }
        if (left >= right) {
            return word;
        }
    }
    return '';
}


  • impl Solution {
    pub fn first_palindrome(words: Vec<String>) -> String {
        for word in words.iter() {
            let s = word.as_bytes();
            let mut left = 0;
            let mut right = s.len() - 1;
            while (left < right) {
                if (s[left] != s[right]) {
                    break;
                }
                left += 1;
                right -= 1;
            }
            if left >= right {
                return word.clone();
            }
        }
        String::new()
    }
}

Solution 2.

  • // OJ: https://leetcode.com/problems/find-first-palindromic-string-in-the-array/
// Time: O(NW)
// Space: O(1)
class Solution {
    bool isPalindrome(string &s) {
        int i = 0, j = s.size() - 1;
        while (i < j && s[i] == s[j]) ++i, --j;
        return i >= j;
    }
public:
    string firstPalindrome(vector<string>& A) {
        for (auto &s : A) {
            if (isPalindrome(s)) return s;
        }
        return "";
    }
};

  • class Solution:
    def firstPalindrome(self, words: List[str]) -> str:
        def check(s):
            i, j = 0, len(s) - 1
            while i < j:
                if s[i] != s[j]:
                    return False
                i += 1
                j -= 1
            return True

        for word in words:
            if check(word):
                return word
        return ''

############

# 2108. Find First Palindromic String in the Array
# https://leetcode.com/problems/find-first-palindromic-string-in-the-array/

class Solution:
    def firstPalindrome(self, words: List[str]) -> str:
        res = ""
        
        for x in words:
            if x == x[::-1]:
                return x
        
        return res


  • class Solution {
    public String firstPalindrome(String[] words) {
        for (var w : words) {
            boolean ok = true;
            for (int i = 0, j = w.length() - 1; i < j && ok; ++i, --j) {
                if (w.charAt(i) != w.charAt(j)) {
                    ok = false;
                }
            }
            if (ok) {
                return w;
            }
        }
        return "";
    }
}

  • func firstPalindrome(words []string) string {
	for _, w := range words {
		ok := true
		for i, j := 0, len(w)-1; i < j && ok; i, j = i+1, j-1 {
			if w[i] != w[j] {
				ok = false
			}
		}
		if ok {
			return w
		}
	}
	return ""
}

  • function firstPalindrome(words: string[]): string {
    for (const word of words) {
        let left = 0;
        let right = word.length - 1;
        while (left < right) {
            if (word[left] !== word[right]) {
                break;
            }
            left++;
            right--;
        }
        if (left >= right) {
            return word;
        }
    }
    return '';
}


  • impl Solution {
    pub fn first_palindrome(words: Vec<String>) -> String {
        for word in words.iter() {
            let s = word.as_bytes();
            let mut left = 0;
            let mut right = s.len() - 1;
            while (left < right) {
                if (s[left] != s[right]) {
                    break;
                }
                left += 1;
                right -= 1;
            }
            if left >= right {
                return word.clone();
            }
        }
        String::new()
    }
}

Discuss

https://leetcode.com/problems/find-first-palindromic-string-in-the-array/discuss/1635048/C%2B%2B-Straightforward

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