Problem
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 <= 105
s
contains only lowercase English letters.
Solution
/**
* @param {string} s
* @return {number}
*/
var minDeletions = function(s) {
var frequencyMap = {};
for (var i = 0; i < s.length; i++) {
frequencyMap[s[i]] = (frequencyMap[s[i]] || 0) + 1;
}
var frequencies = Object.values(frequencyMap).sort((a, b) => b - a);
var duplicatedFrequencies = [];
var result = 0;
for (var j = 0; j < frequencies.length; j++) {
var frequency = frequencies[j];
if (frequency === frequencies[j + 1]) {
duplicatedFrequencies.push(frequency);
continue;
}
while (duplicatedFrequencies.length && frequency > (frequencies[j + 1] || 0) + 1) {
frequency -= 1;
result += duplicatedFrequencies.pop() - frequency;
}
}
while (duplicatedFrequencies.length) {
result += duplicatedFrequencies.pop();
}
return result;
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(1).