(Easy) Can Make Palindrome - LeetCode Contest (in progress)
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Description:
Given a string s
, we make queries on substrings of s
.
For each query queries[i] = [left, right, k]
, we may rearrange the substring s[left], ..., s[right]
, and then choose up to k
of them to replace with any lowercase English letter.
If the substring is possible to be a palindrome string after the operations above, the result of the query is true
. Otherwise, the result is false
.
Return an array answer[]
, where answer[i]
is the result of the i
-th query queries[i]
.
Note that: Each letter is counted individually for replacement so if for example s[left..right] = "aaa"
, and k = 2
, we can only replace two of the letters. (Also, note that the initial string s
is never modified by any query.)
Example :
Input: s = "abcda", queries = [[3,3,0],[1,2,0],[0,3,1],[0,3,2],[0,4,1]] Output: [true,false,false,true,true] Explanation: queries[0] : substring = "d", is palidrome. queries[1] : substring = "bc", is not palidrome. queries[2] : substring = "abcd", is not palidrome after replacing only 1 character. queries[3] : substring = "abcd", could be changed to "abba" which is palidrome. Also this can be changed to "baab" first rearrange it "bacd" then replace "cd" with "ab". queries[4] : substring = "abcda", could be changed to "abcba" which is palidrome.
Constraints:
1 <= s.length, queries.length <= 10^5
0 <= queries[i][0] <= queries[i][1] < s.length
0 <= queries[i][2] <= s.length
s
only contains lowercase English letters.
Solution:
Attempt1 :
Failed one test case , time out exception:
class Solution public List<Boolean> canMakePaliQueries(String s, int[][] queries) if(queries==null||s==null ||s.length()==0||queries.length==0||queries[0].length==0) return null; List<Boolean> list = new ArrayList<Boolean>(); for(int i = 0; i<queries.length;i++) String tmp = ""; int st = queries[i][0]; int en = queries[i][1]; int k = queries[i][2]; boolean test = isPalindrome2(s.substring(st,en+1),k); list.add(test); return list; /* public boolean isPalindrome(String s, int k) int begin = 0; int end = s.length()-1; int times =0; while(begin<end) if(s.charAt(begin)!= s.charAt(end)) if(times <k) times = times+1; else return false; begin++; end--; return true; */ public boolean isPalindrome2(String s, int k) int count =0; HashMap<Character, Integer> map = new HashMap<>(); for(int i = 0; i<s.length(); i++) if(!map.containsKey(s.charAt(i))) int tmp = Count(s,s.charAt(i)); if(tmp%2!=0) map.put(s.charAt(i),tmp); System.out.println(s+" "+ s.length()+" "+map.size()); if(s.length()%2==0) if(map.size()/2<=k) return true; else if(map.size()/2-1<k) return true; return false; public int Count(String s, char a) int count = 0; for(int i =0; i<s.length(); i++) if(s.charAt(i)==a) count++; return count;
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