2657. Find the Prefix Common Array of Two Arrays

/**
 * Problem: LeetCode 2657 - Find the Prefix Common Array of Two Arrays
 * Difficulty: Medium
 * Language: Java
 * Author: CodeByTushu
 */
class Solution {
    public int[] findThePrefixCommonArray(int[] A, int[] B) {
        int n = A.length;
        int[] C = new int[n];
        int[] freq = new int[n + 1];
        int commonCount = 0;

        for (int i = 0; i < n; i++) {
            // Track frequency of A[i]
            if (++freq[A[i]] == 2) {
                commonCount++;
            }

            // Track frequency of B[i]
            if (++freq[B[i]] == 2) {
                commonCount++;
            }

            C[i] = commonCount;
        }

        return C;
    }
}

"""
Problem: LeetCode 2657 - Find the Prefix Common Array of Two Arrays
Difficulty: Medium
Language: Python
Author: CodeByTushu
"""
from typing import List

class Solution:
    def findThePrefixCommonArray(self, A: List[int], B: List[int]) -> List[int]:
        n = len(A)
        C = [0] * n
        freq = [0] * (n + 1)
        common_count = 0

        for i in range(n):
            freq[A[i]] += 1
            if freq[A[i]] == 2:
                common_count += 1

            freq[B[i]] += 1
            if freq[B[i]] == 2:
                common_count += 1

            C[i] = common_count

        return C

/**
 * Problem: LeetCode 2657 - Find the Prefix Common Array of Two Arrays
 * Difficulty: Medium
 * Language: C++
 * Author: CodeByTushu
 */
#include <vector>

using namespace std;

class Solution {
public:
    vector<int> findThePrefixCommonArray(vector<int>& A, vector<int>& B) {
        int n = A.size();
        vector<int> C(n, 0);
        vector<int> freq(n + 1, 0);
        int commonCount = 0;

        for (int i = 0; i < n; ++i) {
            if (++freq[A[i]] == 2) {
                commonCount++;
            }
            if (++freq[B[i]] == 2) {
                commonCount++;
            }
            C[i] = commonCount;
        }

        return C;
    }
};

/**
 * Problem: LeetCode 2657 - Find the Prefix Common Array of Two Arrays
 * Difficulty: Medium
 * Language: JavaScript
 * Author: CodeByTushu
 */
/**
 * @param {number[]} A
 * @param {number[]} B
 * @return {number[]}
 */
var findThePrefixCommonArray = function(A, B) {
    const n = A.length;
    const C = new Array(n);
    const freq = new Uint8Array(n + 1);
    let commonCount = 0;

    for (let i = 0; i < n; i++) {
        if (++freq[A[i]] === 2) {
            commonCount++;
        }
        if (++freq[B[i]] === 2) {
            commonCount++;
        }
        C[i] = commonCount;
    }

    return C;
};