Zigzag Conversion
Problem Description
Question
The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this:
And then read line by line: "PAHNAPLSIIGYIR"
Example 1:
Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"
Example 2:
Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:
Example 3:
Input: s = "A", numRows = 1
Output: "A"
Constraints:
1 <= s.length <= 1000sconsists of English letters (lower-case and upper-case),','and'.'.1 <= numRows <= 1000
Solve it on LeetCode
Approaches
1. Zigzag Pattern Simulation
Intuition:
The problem asks to reorder the given string in a specified zigzag pattern across multiple rows. The basic idea here is direct simulation by creating an array of strings, each representing a row in the zigzag pattern.
Steps:
- We iterate over each character in the string and decide which row of the zigzag it belongs to.
- This is determined by moving up and down the rows in a sequential pattern.
- Once the pattern is built, we can concatenate all the rows to get the final string.
Code:
Complexity Analysis
- Time Complexity: O(n) where (n) is the length of the input string. Each character is processed once.
- Space Complexity: O(n) to store the strings.