Question

1616. Split Two Strings to Make Palindrome

中文文档

Description

You are given two strings a and b of the same length. Choose an index and split both strings at the same index, splitting a into two strings: aprefix and asuffix where a = aprefix + asuffix, and splitting b into two strings: bprefix and bsuffix where b = bprefix + bsuffix. Check if aprefix + bsuffix or bprefix + asuffix forms a palindrome.

When you split a string s into sprefix and ssuffix, either ssuffix or sprefix is allowed to be empty. For example, if s = "abc", then "" + "abc", "a" + "bc", "ab" + "c" , and "abc" + "" are valid splits.

Return true_ if it is possible to form__ a palindrome string, otherwise return _false.

Notice that x + y denotes the concatenation of strings x and y.

 

Example 1:

Input: a = "x", b = "y"
Output: true
Explaination: If either a or b are palindromes the answer is true since you can split in the following way:
aprefix = "", asuffix = "x"
bprefix = "", bsuffix = "y"
Then, aprefix + bsuffix = "" + "y" = "y", which is a palindrome.

Example 2:

Input: a = "xbdef", b = "xecab"
Output: false

Example 3:

Input: a = "ulacfd", b = "jizalu"
Output: true
Explaination: Split them at index 3:
aprefix = "ula", asuffix = "cfd"
bprefix = "jiz", bsuffix = "alu"
Then, aprefix + bsuffix = "ula" + "alu" = "ulaalu", which is a palindrome.

 

Constraints:

• 1 <= a.length, b.length <= 105
• a.length == b.length
• a and b consist of lowercase English letters

Solutions

Solution 1

class Solution:
  def checkPalindromeFormation(self, a: str, b: str) -> bool:
    def check1(a: str, b: str) -> bool:
      i, j = 0, len(b) - 1
      while i < j and a[i] == b[j]:
        i, j = i + 1, j - 1
      return i >= j or check2(a, i, j) or check2(b, i, j)

    def check2(a: str, i: int, j: int) -> bool:
      return a[i : j + 1] == a[i : j + 1][::-1]

    return check1(a, b) or check1(b, a)

class Solution {
  public boolean checkPalindromeFormation(String a, String b) {
    return check1(a, b) || check1(b, a);
  }

  private boolean check1(String a, String b) {
    int i = 0;
    int j = b.length() - 1;
    while (i < j && a.charAt(i) == b.charAt(j)) {
      i++;
      j--;
    }
    return i >= j || check2(a, i, j) || check2(b, i, j);
  }

  private boolean check2(String a, int i, int j) {
    while (i < j && a.charAt(i) == a.charAt(j)) {
      i++;
      j--;
    }
    return i >= j;
  }
}

class Solution {
public:
  bool checkPalindromeFormation(string a, string b) {
    return check1(a, b) || check1(b, a);
  }

private:
  bool check1(string& a, string& b) {
    int i = 0, j = b.size() - 1;
    while (i < j && a[i] == b[j]) {
      ++i;
      --j;
    }
    return i >= j || check2(a, i, j) || check2(b, i, j);
  }

  bool check2(string& a, int i, int j) {
    while (i <= j && a[i] == a[j]) {
      ++i;
      --j;
    }
    return i >= j;
  }
};

func checkPalindromeFormation(a string, b string) bool {
  return check1(a, b) || check1(b, a)
}

func check1(a, b string) bool {
  i, j := 0, len(b)-1
  for i < j && a[i] == b[j] {
    i++
    j--
  }
  return i >= j || check2(a, i, j) || check2(b, i, j)
}

func check2(a string, i, j int) bool {
  for i < j && a[i] == a[j] {
    i++
    j--
  }
  return i >= j
}

function checkPalindromeFormation(a: string, b: string): boolean {
  const check1 = (a: string, b: string) => {
    let i = 0;
    let j = b.length - 1;
    while (i < j && a.charAt(i) === b.charAt(j)) {
      i++;
      j--;
    }
    return i >= j || check2(a, i, j) || check2(b, i, j);
  };

  const check2 = (a: string, i: number, j: number) => {
    while (i < j && a.charAt(i) === a.charAt(j)) {
      i++;
      j--;
    }
    return i >= j;
  };
  return check1(a, b) || check1(b, a);
}

impl Solution {
  pub fn check_palindrome_formation(a: String, b: String) -> bool {
    fn check1(a: &[u8], b: &[u8]) -> bool {
      let (mut i, mut j) = (0, b.len() - 1);
      while i < j && a[i] == b[j] {
        i += 1;
        j -= 1;
      }
      if i >= j {
        return true;
      }
      check2(a, i, j) || check2(b, i, j)
    }

    fn check2(a: &[u8], mut i: usize, mut j: usize) -> bool {
      while i < j && a[i] == a[j] {
        i += 1;
        j -= 1;
      }
      i >= j
    }

    let a = a.as_bytes();
    let b = b.as_bytes();
    check1(a, b) || check1(b, a)
  }
}