Given a palindromic string of lowercase English letters palindrome
, replace exactly one character with any lowercase English letter so that the resulting string is not a palindrome and that it is the lexicographically smallest one possible.
Return the resulting string. If there is no way to replace a character to make it not a palindrome, return an empty string.
A string a
is lexicographically smaller than a string b
(of the same length) if in the first position where a
and b
differ, a
has a character strictly smaller than the corresponding character in b
. For example, "abcc"
is lexicographically smaller than "abcd"
because the first position they differ is at the fourth character, and 'c'
is smaller than 'd'
.
Example 1:
Input: palindrome = "abccba" Output: "aaccba" Explanation: There are many ways to make "abccba" not a palindrome, such as "zbccba", "aaccba", and "abacba". Of all the ways, "aaccba" is the lexicographically smallest.
Example 2:
Input: palindrome = "a" Output: "" Explanation: There is no way to replace a single character to make "a" not a palindrome, so return an empty string.
Example 3:
Input: palindrome = "aa" Output: "ab"
Example 4:
Input: palindrome = "aba" Output: "abb"
Constraints:
1 <= palindrome.length <= 1000
palindrome
consists of only lowercase English letters.
Related Topics:
String, Greedy
// OJ: https://leetcode.com/problems/break-a-palindrome/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
string breakPalindrome(string s) {
int N = s.size();
if (N == 1) return "";
for (int i = 0, end = N / 2; i < end; ++i) {
if (s[i] != 'a') {
s[i] = 'a';
return s;
}
}
s[N - 1] = 'b';
return s;
}
};