[leetcode-in-go] 0006-ZigZag Conversion-优快云博客

本文链接：https://blog.youkuaiyun.com/shida_csdn/article/details/94495742

本文介绍了一种将字符串以Z字形排列并按行读取的算法实现，通过分析等差数列规律，提供了Go语言的具体代码示例，展示了如何处理不同行数的特殊情况。

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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:

func convert(text string, nRows int) string

convert(“PAYPALISHIRING”, 3) should return “PAHNAPLSIIGYIR”.

解题思路

按图找规律（类似等差数列）

func convert(text string, nRows int) string {

	var result string
	
	if nRows == 1 {
		return text
	}

	p := 2*nRows - 2

	length := len(text)

	for i := 0; i < nRows; i++ {

		// 首/尾特殊处理
		if i == 0 || i == nRows-1 {
			for j := 0; ; j++ {
				if i+j*p < length {
					result += string(text[i+j*p ])
				} else {
					break
				}
			}
		} else {
			// 其他行，奇偶判断，分别处理
			first := i
			second := i + (p - 2*i)
			if first < length {
				result += string(text[first])
			} else {
				continue
			}
			if second < length {
				result += string(text[second])
			} else {
				continue
			}
			for j := 1; ; j++ {
				if first+j*p < length {
					result += string(text[first+j*p])
				} else {
					break
				}
				if second+j*p < length {
					result += string(text[second+j*p])
				} else {
					break
				}
			}
		}
	}
	return result
}