Cross Comparison

What is the name for comparing element in two different arrays?

Comparing elements across two different arrays has a few common names:

• Cross array comparison
• Inter-array comparison
• Cross-array element comparison
• Comparing array elements pairwise

The main idea is that the elements being compared come from two separate arrays, rather than comparing elements within the same array.

Some examples of problems involving cross-array comparison:

• Comparing arrays element-wise to check if they are identical
• Merging two sorted arrays into a larger sorted array
• Finding the minimum/maximum element across two arrays
• Finding the median of two sorted arrays
• Set intersection - finding common elements across two arrays
• Pairwise min/max of two arrays of numbers

So in summary, “cross-array comparison” or “inter-array comparison” refers to comparing or combining elements from two distinct arrays, rather than comparing elements within the same array. The “cross-array” terminology emphasizes that the arrays are separate but their elements are being compared.

CrapGPT

The act of comparing elements between two different arrays doesn’t have a specific technical name, but it is often part of algorithms that perform “array matching,” “element-wise comparison,” or “cross-referencing.” This kind of operation is common in algorithms dealing with sorting, searching, and set operations like union or intersection.

It is more of a cross comparison. Because Pairwise Comparison uses one array.

Yes, you’re correct. In the context of two different arrays, the comparison can be referred to as “cross comparison.” Pairwise comparison generally implies comparing elements within the same array. In cross comparison, you’re typically comparing each element in one array to each element in another, which can be part of more complex operations like finding intersections, unions, or differences between arrays.

The problem “Checking for a Common Element” involves determining whether two arrays A and B have at least one common element. This is a basic problem in array manipulation and can be solved using various approaches, including brute-force comparison, using hash sets, or sorting and then comparing.

Brute-force - Java

In this approach, you would use two nested loops to compare every pair of elements from arrays A and B.

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public class Main {
    public static boolean checkCommon(int[] A, int[] B) {
        for(int i = 0; i < A.length; i++) {
            for(int j = 0; j < B.length; j++) {
                if(A[i] == B[j]) return true;
            }
        }
        return false;
    }
}

Brute-force - C++

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#include <iostream>
using namespace std;

bool checkCommon(int A[], int B[], int n) {
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) {
            if(A[i] == B[j]) return true;
        }
    }
    return false;
}

Brute-force - Python

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def checkCommon(A, B):
    for i in A:
        for j in B:
            if i == j:
                return True
    return False

Hash Set - Java

You could also use a hash set to make the comparison more efficient.

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import java.util.HashSet;

public class Main {
    public static boolean checkCommon(int[] A, int[] B) {
        HashSet<Integer> set = new HashSet<>();
        for(int i : A) {
            set.add(i);
        }
        for(int j : B) {
            if(set.contains(j)) return true;
        }
        return false;
    }
}

Hash Set - C++

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#include <iostream>
#include <unordered_set>
using namespace std;

bool checkCommon(int A[], int B[], int n) {
    unordered_set<int> set;
    for(int i = 0; i < n; i++) {
        set.insert(A[i]);
    }
    for(int j = 0; j < n; j++) {
        if(set.find(B[j]) != set.end()) return true;
    }
    return false;
}

Hash Set - Python

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def checkCommon(A, B):
    s = set(A)
    for j in B:
        if j in s:
            return True
    return False

By using a hash set, the time complexity is reduced to O(n) for adding elements and O(n) for checking, making it a more efficient solution than the brute-force approach.