Given a sequence of Words and the Order of the alphabet. The order of the alphabet is some permutation of lowercase letters. The task is to check whether the given words are sorted lexicographically according to order of alphabets. Return “True” if it is, otherwise “False”.
Input : Words = [“hello”, “leetcode”], Order = “habcldefgijkmnopqrstuvwxyz”
Output : true
Input : Words = [“word”, “world”, “row”], Order = “abcworldefghijkmnpqstuvxyz”
Output : false
Explanation : As ‘d’ comes after ‘l’ in Order, thus words > words, hence the sequence is unsorted.
Approach : The words are sorted lexicographically if and only if adjacent words are sorted. This is because order is transitive i:e if a <= b and b <= c, implies a <= c.
So our goal it to check whether all adjacent words a and b have a <= b.
To check whether for two adjacent words a and b, a <= b holds we can find their first difference. For example, "seen" and "scene" have a first difference of e and c. After this, we compare these characters to the index in order.
We have to deal with the blank character effectively. If for example, we are comparing "add" to "addition", this is a first difference of (NULL) vs "i".
Below is the implementation of above approach :
Time Complexity: O(N), where N is the total number of characters in all words.
Auxiliary Space: O(1)
- Find alphabetical order such that words can be considered sorted
- Check if value exists in level-order sorted complete binary tree
- Check if the given string of words can be formed from words present in the dictionary
- Merge K sorted Doubly Linked List in Sorted Order
- Print words of a string in reverse order
- Reorder the position of the words in alphabetical order
- Sort the words in lexicographical order in Python
- Python | Sort words of sentence in ascending order
- Check if a string contains only alphabets in Java using Lambda expression
- Check if a string contains only alphabets in Java using ASCII values
- Rearrange a string in sorted order followed by the integer sum
- Print all permutations in sorted (lexicographic) order
- Merging two unsorted arrays in sorted order
- Print Binary Tree levels in sorted order | Set 2 (Using set)
- Print Binary Tree levels in sorted order
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to firstname.lastname@example.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.