What is the method to merge and remove duplicates in C language arrays?

There are several methods to merge and remove duplicates in C language arrays.

1. Using nested loops to iterate through two arrays and store non-duplicate elements in a new array. This method has a higher time complexity of O(n^2).
2. First, sort the two arrays separately, then use the two-pointer method to merge and remove duplicates. Begin by comparing the first elements of the two arrays, storing the smaller element in a new array and moving the corresponding pointer one position ahead. If the two elements are equal, only store one element and move both pointers forward. Repeat this process until both arrays have been traversed, obtaining the merged array. This method has a time complexity of O(nlogn), where n is the total length of the two arrays.
3. To implement de-duplication, use a hash table. First, iterate through the first array and store each element in the hash table. Then, iterate through the second array and for each element, check if it already exists in the hash table. If it does not exist, store it in the hash table. Finally, iterate through the hash table and store all unique elements in a new array. This method has a time complexity of O(n), where n is the total length of the two arrays. However, it requires additional space to store the hash table.

In summary, using a hash table method is more efficient but requires extra space; while the two-pointer method is less efficient but does not require extra space. The choice of method depends on specific needs.