ZigZag Conversion

最新推荐文章于 2022-04-17 19:49:20 发布

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本文介绍了一种将字符串以Z形排列方式转换的方法，并提供了一个Java实现示例。该算法适用于给定行数的Z形排列，通过逐行读取形成最终的字符串。

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 text, int nRows);

convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".

public class Solution {
    public String convert(String s, int nRows) {
        if (s == null || s.length() <= nRows || nRows <= 1) return s;
        StringBuffer sb = new StringBuffer();
        // the first row
        for (int i = 0; i < s.length(); i += (nRows - 1) * 2) {
            sb.append(s.charAt(i));
        }
        
        for (int i = 1; i < nRows - 1; i++) {
            for (int j = i; j < s.length(); j+= (nRows - 1) * 2) {
                sb.append(s.charAt(j));
                if (j + (nRows - i - 1) * 2 < s.length()) {
                    sb.append(s.charAt(j + (nRows - i - 1) * 2));
                }
            }
        }
        // the last row
        for (int i = nRows - 1; i < s.length(); i += (nRows - 1) * 2) {
            sb.append(s.charAt(i));
        }
        return sb.toString();
    }
}

Reference:

http://tech-lightnight.blogspot.com/2012/12/zigzag-conversion.html