Finding Duplicates in a List
Question: You have a list of integers, and you want to find any duplicates in that list.
Which collection would you use for efficient duplicate detection?
Answer: I would use a HashSet to track seen integers while iterating through the list.
If an integer already exists in the HashSet, it is a duplicate.
Here’s how you could implement this:
package com.example.demo;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
public class Test {
public static void main(String[] args) {
List<Integer> li = Arrays.asList(12,12,1,2,3,4,2,4);
HashSet<Integer> hs = new HashSet<>();
for(Integer i : li) {
if(hs.contains(i)) {
System.out.println(i);
}
hs.add(i);
}
}
}
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