2657. Find the Prefix Common Array of Two Arrays
Medium
191
6

You are given two 0-indexed integer permutations `A` and `B` of length `n`.

A prefix common array of `A` and `B` is an array `C` such that `C[i]` is equal to the count of numbers that are present at or before the index `i` in both `A` and `B`.

Return the prefix common array of `A` and `B`.

A sequence of `n` integers is called a permutation if it contains all integers from `1` to `n` exactly once.

Example 1:

```Input: A = [1,3,2,4], B = [3,1,2,4]
Output: [0,2,3,4]
Explanation: At i = 0: no number is common, so C = 0.
At i = 1: 1 and 3 are common in A and B, so C = 2.
At i = 2: 1, 2, and 3 are common in A and B, so C = 3.
At i = 3: 1, 2, 3, and 4 are common in A and B, so C = 4.
```

Example 2:

```Input: A = [2,3,1], B = [3,1,2]
Output: [0,1,3]
Explanation: At i = 0: no number is common, so C = 0.
At i = 1: only 3 is common in A and B, so C = 1.
At i = 2: 1, 2, and 3 are common in A and B, so C = 3.
```

Constraints:

• `1 <= A.length == B.length == n <= 50`
• `1 <= A[i], B[i] <= n`
• `It is guaranteed that A and B are both a permutation of n integers.`
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