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MinimumDeletionsToMakeUniqueCharacterFrequency.java
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MinimumDeletionsToMakeUniqueCharacterFrequency.java
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package Leetcode;
import java.util.HashSet;
import java.util.Set;
/**
* @author kalpak
*
* A string s is called good if there are no two different characters in s that have the same frequency.
*
* Given a string s, return the minimum number of characters you need to delete to make s good.
*
* The frequency of a character in a string is the number of times it appears in the string.
*
* For example, in the string "aab", the frequency of 'a' is 2, while the frequency of 'b' is 1.
*
* Example 1:
* Input: s = "aab"
* Output: 0
* Explanation: s is already good.
*
* Example 2:
* Input: s = "aaabbbcc"
* Output: 2
* Explanation: You can delete two 'b's resulting in the good string "aaabcc".
* Another way it to delete one 'b' and one 'c' resulting in the good string "aaabbc".
*
* Example 3:
* Input: s = "ceabaacb"
* Output: 2
* Explanation: You can delete both 'c's resulting in the good string "eabaab".
* Note that we only care about characters that are still in the string at the end (i.e. frequency of 0 is ignored).
*
*
* Constraints:
*
* 1 <= s.length <= 10^5
* s contains only lowercase English letters.
*
*/
public class MinimumDeletionsToMakeUniqueCharacterFrequency {
public static int minDeletions(String s) {
int[] frequencies = new int[26];
int result = 0;
Set<Integer> isUsed = new HashSet<>();
// Calculate the frequencies if each characters in the string
for(int i = 0; i < s.length(); i++) {
frequencies[s.charAt(i) - 'a']++;
}
for(int i = 0; i < frequencies.length; i++) {
int currentFreq = frequencies[i];
while(currentFreq > 0 && isUsed.contains(currentFreq)) {
currentFreq--;
result++;
}
isUsed.add(currentFreq);
}
return result;
}
public static void main(String[] args) {
String s = "aaabbbcc";
System.out.println("The minimum number of deletions required: " + minDeletions(s));
s = "ceabaacb";
System.out.println("The minimum number of deletions required: " + minDeletions(s));
}
}