n are present exactly once.

We can use an frequency array to track the frequency of the element structure to track which elements have been encountered in both arrays.

We need to count common element in A and B upto an index.

So, for each element in A and B, we increment its corresponding counter in cnt. If the frequency of that element reaches 2, it indicates the element is found in both arrays up to the current index i.

Code

[{"language":"Java","code":"class Solution {\n    public int[] findThePrefixCommonArray(int[] A, int[] B) {\n        int n = A.length;\n        int[] freq = new int[n + 1]; // Auxiliary array to track frequencies\n        int[] ans = new int[n]; // Result array\n        int common = 0; // Count of common elements\n\n        for (int i = 0; i < n; i++) {\n            // Increment frequency of A[i]; if it reaches 2, increment common count\n            if (++freq[A[i]] == 2) {\n\t            common++;\n\t        }\n            // Increment frequency of B[i]; if it reaches 2, increment common count\n            if (++freq[B[i]] == 2) {\n\t            common++;\n\t        }\n            ans[i] = common; // Store common count up to index i\n        }\n        return ans;\n    }\n}","lang":"java","html":"<pre class=\"shiki shiki-themes github-light github-dark\" style=\"background-color:#fff;--shiki-dark-bg:#24292e;color:#24292e;--shiki-dark:#e1e4e8\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">class</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\"> Solution</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> {</span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">    public</span><span style=\"color:#D73A49;--shiki-dark:#F97583\"> int</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">[] </span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\">findThePrefixCommonArray</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">(</span><span style=\"color:#D73A49;--shiki-dark:#F97583\">int</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">[] </span><span style=\"color:#E36209;--shiki-dark:#FFAB70\">A</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">, </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">int</span><span style=\"color:#24

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