Find intersection of two arrays (unique)
Hard
Java
Java Arrays
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Problem Statement
Task: return unique intersection of a and b.
Input Format
An integer n (size of array a)
Then n integers
An integer m (size of array b)
Then m integers
Then n integers
An integer m (size of array b)
Then m integers
Output Format
An array containing unique elements present in both a and b.
Example
5 1 2 2 3 4 4 2 2 4 6
[2, 4]
Constraints
• n ≥ 0, m ≥ 0
• Result should contain unique elements only
• Result should contain unique elements only
Concept Explanation
We find elements common to both arrays.
Each common value should appear only once in result.
Each common value should appear only once in result.
Step-by-Step Explanation
1.Read arrays a and b.
2.Insert all elements of a into a HashSet.
3.Create another empty HashSet for result.
4.Loop through array b:
• If element exists in first set, add it to result set.
5.Convert result set into an array.
6.Return the array.
2.Insert all elements of a into a HashSet.
3.Create another empty HashSet for result.
4.Loop through array b:
• If element exists in first set, add it to result set.
5.Convert result set into an array.
6.Return the array.
Concept Explanation
We find elements common to both arrays.
Each common value should appear only once in result.
Each common value should appear only once in result.
Step-by-Step Explanation
1.Read arrays a and b.
2.Insert all elements of a into a HashSet.
3.Create another empty HashSet for result.
4.Loop through array b:
• If element exists in first set, add it to result set.
5.Convert result set into an array.
6.Return the array.
2.Insert all elements of a into a HashSet.
3.Create another empty HashSet for result.
4.Loop through array b:
• If element exists in first set, add it to result set.
5.Convert result set into an array.
6.Return the array.
Input / Output Format
Input Format
An integer n (size of array a)
Then n integers
An integer m (size of array b)
Then m integers
Then n integers
An integer m (size of array b)
Then m integers
Output Format
An array containing unique elements present in both a and b.
Constraints
• n ≥ 0, m ≥ 0
• Result should contain unique elements only
• Result should contain unique elements only
Examples
Input:
5
1 2 2 3 4
4
2 2 4 6
Output:
[2, 4]
Example Solution (Public)
static int[] intersection(int[] a,int[] b){java.util.HashSet<Integer> s=new java.util.HashSet<>();for(int x:a) s.add(x);java.util.HashSet<Integer> out=new java.util.HashSet<>();for(int x:b) if(s.contains(x)) out.add(x);int[] r=new int[out.size()];int i=0;for(int x:out) r[i++]=x;return r;}
Official Solution Code
static int[] intersection(int[] a,int[] b){java.util.HashSet<Integer> s=new java.util.HashSet<>();for(int x:a) s.add(x);java.util.HashSet<Integer> out=new java.util.HashSet<>();for(int x:b) if(s.contains(x)) out.add(x);int[] r=new int[out.size()];int i=0;for(int x:out) r[i++]=x;return r;}
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