Three of my accounts recently achieved the #1, #2 and #3 leetcode ratings in South Korea. lol 😂

Leetcode contest speed-run global rank 2nd

Leetcode contest speed-run global rank 3rd

3213. Construct String with Minimum Cost

You are given a string target, an array of strings words, and an integer array costs, both arrays of the same length.

Imagine an empty string s.

You can perform the following operation any number of times (including zero):

• Choose an index i in the range [0, words.length - 1].
• Append words[i] to s.
• The cost of operation is costs[i].

Return the minimum cost to make s equal to target. If it’s not possible, return -1.

3212. Count Submatrices With Equal Frequency of X and Y

Given a 2D character matrix grid, where grid[i][j] is either 'X', 'Y', or '.', return the number of submatrices that contains:

• grid[0][0]
• an equal frequency of 'X' and 'Y'.
• at least one 'X'.

3211. Generate Binary Strings Without Adjacent Zeros

You are given a positive integer n.

A binary string x is valid if all substrings of x of length 2 contain at least one "1".

Return all valid strings with length n, in any order.

3210. Find the Encrypted String

You are given a string s and an integer k. Encrypt the string using the following algorithm:

• For each character c in s, replace c with the kth character after c in the string (in a cyclic manner).

Return the encrypted string.