LeetCode 刷题之 ZigZag Conversion

最新推荐文章于 2021-03-20 20:07:40 发布

David_Hernandez

最新推荐文章于 2021-03-20 20:07:40 发布

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分类专栏： LeetCode

本文链接：https://blog.youkuaiyun.com/kisslotus/article/details/79604144

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本文介绍了一种将字符串以ZigZag形式排列并按行读取的算法实现。该算法通过特定的循环和条件判断，实现了字符串PAYPALISHIRING在指定行数下的ZigZag模式转换，最终返回转换后的字符串。

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LeetCode 刷题之 ZigZag Conversion

/**
 * @Time : 18/03/2018 15:59
 * @Author : lotus
 * @File : ZigzagPattern.java
 * @Software: IntelliJ IDEA
 * @Desc :
 * @license : Copyright(C), Alex
 * @Contact : alex.cs.monash@gmail.com
 */

import java.util.Scanner;

/**
 * Question: 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 text, int nRows);
 * convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".
 */

public class ZigzagPattern {

    public String convert(String s, int numRows) {
        if (s == null || s.length() == 0 || numRows <= 1 || s.length() <= numRows) {
            return s;
        }

        final int batch = 2 * numRows - 2;
        final int length = s.length();
        final char[] chars = s.toCharArray();
        StringBuilder output = new StringBuilder(length);
        for (int i = 0; i < length; i += batch) {
            output.append(chars[i]);
        }

        for (int i = 1; i < numRows - 1; i++) {
            for (int j = 0; j + i < length; j += batch) {
                output.append(chars[j + i]);
                if (j + batch - i < length) {
                    output.append(chars[j + batch - i]);
                }
            }
        }

        for (int i = numRows - 1; i < length; i += batch) {
            output.append(chars[i]);
        }

        return output.toString();
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.next();
        int rows = Integer.parseInt(scanner.next());
        ZigzagPattern zigzag = new ZigzagPattern();
        System.out.println(zigzag.convert(input, rows));

    }
}