leetcode——6 ZigZag Conversion(折线行列输出问题)

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".

Hide Tags: String

解题思路:

因为行数为变量,因此我们需要找到每一行的规律。例如:当行数numRows=4时,则ZigZag应该按下列方式排列

不难看出,满数为4的列之间的步数为4,实际上,此时步的规律为:step=2*numRows-2 =2*4-2=6

0        6       12       18

1     5  7    11 13    17 19

2  4     8 10    14 16    20

3        9       15       21

接着我们看非满数的列,不难看出此类列的每一行都只有一个数,就拿第二例为例:1 5 7 11 13 17 19,先看看

1 5 7 ,“1”与“5”之间的步数为:step1=(numRows-1-1)*2=(4-1-1)*2=4 ,而“5”与“7”之间的步数为:step2=step-step1=6-4=2.

不难看出:假设我们所在的行为第i行(i<numRows) step=2*numRows-2 ,step1=(numRows-1-i)*2,step2=step-step1

我们所找到的规律并不适合numRows=1的情况,因此需要将它单独拿出来套路

代码如下:

	public static String convert(String s,int numRows)
	{
		//当字符串的长度为0或行数为1时,直接返回s
		if (s.length()==0||numRows==1)
		{
			return s;
		}
		//new一个StringBuilder,用于 字符串的拼凑
		StringBuilder sb=new StringBuilder();
		int step=2*numRows-2;
		for (int i = 0; i < numRows; i++)
		{
			//第一行与最后一行,中间的步数为:step=2*numRows-2
			if (i==0||i==numRows-1)
			{
				for (int j = i; j < s.length(); j=j+step)
				{
					sb.append(s.charAt(j));
				}
			}
			else
			{
				int j=i;
				//设置一个step1与step2交替变换的标识
				boolean flag=true;
				int step1=2*(numRows-1-i);
				int step2=step-step1;
				while (j<s.length())
				{
					sb.append(s.charAt(j));
					if (flag)
					{
						j=j+step1;
					}
					else
					{
						j=j+step2;
					}
					flag=!flag;
				}
			}
		}
		//将StringBuilder转换成String类型
		return sb.toString();

	}
时间: 2024-10-02 17:53:59

leetcode——6 ZigZag Conversion(折线行列输出问题)的相关文章

leetcode -day16 ZigZag Conversion

1.  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 b

【LeetCode】ZigZag Conversion

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

leetCode 6. ZigZag Conversion 字符串 (上传费劲)

6. ZigZag Conversion 题目:https://leetcode.com/problems/zigzag-conversion/ string convert2(string s, int numRows) { if (s.length() < 2 || numRows < 2) return s; int cycle = 2 * numRows - 2; string tmp; string result; for (int i = 0; i < numRows; i+

[LeetCode][JavaScript]ZigZag Conversion

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

leetCode 6. ZigZag Conversion 字符串

6. ZigZag Conversion

LeetCode 6 - ZigZag Conversion

原题如下: 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: "PAHN

LeetCode 6 ZigZag Conversion 模拟 难度:0

https://leetcode.com/problems/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

LeetCode 6 ZigZag Conversion(规律)

题目来源:https://leetcode.com/problems/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

[LeetCode][Python]ZigZag Conversion

# -*- coding: utf8 -*-'''__author__ = '[email protected]'https://oj.leetcode.com/problems/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