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  1. import java.util.HashMap;
  2. import java.util.Map;
  3.  
  4. class Main {
  5.     public static int minOperationsToDestroyArray(int[] arr) {
  6.         Map<Integer, Integer> freqMap = new HashMap<>();
  7.         for (int num : arr){
  8.             freqMap.put(num, freqMap.getOrDefault(num, 0) + 1);
  9.         }
  10.  
  11.         int minOperations = 0;
  12.         for ( Map.Entry<Integer, Integer> entry : freqMap.entrySet()) {
  13.             int freq = entry.getValue();
  14.             if (freq == 1) {
  15.                 return -1;
  16.             } else {
  17.                 //we can consume 2 or 3 elements in one operation
  18.                 // for min .. see how many 3's can be removed
  19.                 // remainder can be 1 or 2 or 0 if 0 no extra operation
  20.                 // if remainder is 1 it means that it can be coupled with a 3 to form 4 thats 2 + 2 .. thats 2 operations now
  21.                 // remainder 2 then add 1 or if 1 then also add 1 .. thats the meaning of freq % 3 != 0 ? 1 : 0
  22.  
  23.                 minOperations += freq / 3 + (freq % 3 != 0 ? 1 : 0);
  24.             }
  25.         }
  26.         return minOperations;
  27.     }
  28.  
  29.     public static void main(String[] args) {
  30.         int[] arr = {1, 5, 5, 1, 1, 8, 8, 10, 10};
  31.         int minOps = minOperationsToDestroyArray(arr);
  32.         if (minOps == -1) {
  33.             System.out.println("it's not possible to destroy the array.");
  34.         } else {
  35.             System.out.println("Minimum number of operations to destroy the array: " + minOps);
  36.         }
  37.     }
  38. }
  39.  
Success #stdin #stdout 0.12s 55580KB
comments (?)
stdin 
Standard input is empty
stdout 
Minimum number of operations to destroy the array: 4
https://ideone.com/f4n1Jy
language:
Java (HotSpot 12)
created:
2 days ago
visibility:
public

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