Given a string and number of rows ‘n’. Print the string formed by concatenating n rows when input string is written in row-wise Zig-Zag fashion.
Input: str = "ABCDEFGH" n = 2 Output: "ACEGBDFH" Explanation: Let us write input string in Zig-Zag fashion in 2 rows. A C E G B D F H Now concatenate the two rows and ignore spaces in every row. We get "ACEGBDFH" Input: str = "GEEKSFORGEEKS" n = 3 Output: GSGSEKFREKEOE Explanation: Let us write input string in Zig-Zag fashion in 3 rows. G S G S E K F R E K E O E Now concatenate the two rows and ignore spaces in every row. We get "GSGSEKFREKEOE"
We strongly recommend that you click here and practice it, before moving on to the solution.
The idea is to traverse the input string. Every character has to go to one of the rows. One by one add all characters to different rows. Below is algorithm:
1) Create an array of n strings, arr[n] 2) Initialize direction as "down" and row as 0. The direction indicates whether we need to move up or down in rows. 3) Traverse the input string, do following for every character. a) Append current character to string of current row. b) If row number is n-1, then change direction to 'up' c) If row number is 0, then change direction to 'down' d) If direction is 'down', do row++. Else do row--. 4) One by one print all strings of arr.
Below is implementation of above idea.
Time Complexity: O(len) where len is length of input string.
Auxiliary Space: O(len)
Thanks to Gaurav Ahirwar for suggesting above solution.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
- Lexicographical concatenation of all substrings of a string
- Ropes Data Structure (Fast String Concatenation)
- Print shortest path to print a string on screen
- Print the longest prefix of the given string which is also the suffix of the same string
- Concatenation of two strings in PHP
- Pairs whose concatenation contain all digits
- Number of pairs with Pandigital Concatenation
- Print all subsequences of a string
- Count of three non-overlapping sub-strings which on concatenation forms a palindrome
- Print all funny words in a string
- Given a string, print all possible palindromic partitions
- Print the first and last character of each word in a String
- Print string of odd length in 'X' format
- Print last character of each word in a string
- Print all palindrome permutations of a string