6. ZigZag Conversion

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P   A   H   N
A P L S I I G
Y   I   R

And then read line by line: "PAHNAPLSIIGYIR"

Write the code that will take a string and make this conversion given a number of rows:

string convert(string s, int numRows);

Example 1:

Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"

Example 2:

Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:
P     I    N
A   L S  I G
Y A   H R
P     I

Example 3:

Input: s = "A", numRows = 1
Output: "A"

Constraints:

• 1 <= s.length <= 1000
• s consists of English letters (lower-case and upper-case), ',' and '.'.
• 1 <= numRows <= 1000

# @lc code=start
using LeetCode

function zig_zag_convert(s::String, num_rows::Int)::String
    if num_rows == 1 || num_rows >= length(s)
        s
    else
        table = [Char[] for _ in 1:num_rows]
        i, dir = 1, 1
        for x in s
            push!(table[i], x)
            if i == 1
                dir = 1
            elseif i == num_rows
                dir = -1
            end
            i += dir
        end
        join(Iterators.flatten(table))
    end
end
# @lc code=end

zig_zag_convert (generic function with 1 method)

This page was generated using DemoCards.jl and Literate.jl.