Microsoft OA

Given a string S consisting of N lowercase letters, return the minimum number of letters that must be deleted to obtain a word in which every letter occurs a unique number of times

没有想到要再存一个HashMap, appearance to character mapping

package UniqueCharacter;

import java.util.HashMap;
import java.util.Map;

public class Solution {
    public static int charCountToDelete(String s) {
        HashMap<Character, Integer> map = new HashMap<>();
        for (char c : s.toCharArray()) {
            map.put(c, map.getOrDefault(c, 0) + 1);
        }

        int res = 0;
        HashMap<Integer, Character> intToCharMap = new HashMap<>();
        for (Map.Entry<Character, Integer> entry : map.entrySet()) {
            int value = entry.getValue();
            while (intToCharMap.containsKey(value)) {
                res ++; // need to delete
                value --;
            }
            intToCharMap.put(value, entry.getKey());
        }
        return res;
    }

    public static void main(String[] args) {
        int res = charCountToDelete("aaaabbbbcccdde");
        System.out.printf("result is %d\n", res);
        int res2 = charCountToDelete("aaaabbbb");
        System.out.printf("result is %d\n", res2);
        int res3 = charCountToDelete("aaaabbbccd");
        System.out.printf("result is %d\n", res3);
    }
}