CareerCup

One way could be iterate over the childs starting from father and increament a count. Once you reach n-1 count then push all those childs to a stack or somewhere. Now, you can simply list their childrens from hashmap or the input given.

One way could be to create a trie of the char array and traverse the tree to find if strings generated match any of the dictionary.

One way could be start processing from the center of the matrix. If value x you are searching for is less than mid (center of the matrix) then move to upper-left matrix, if value x is greater than mid then move to lower-right matrix. Stop when you find the element x or element is not there.