[Leetcode] (python): 006-zigzag Conversion

Source of the topic:

https://leetcode.com/problems/zigzag-conversion/

Test Instructions Analysis:

This topic is the subject of string processing. Enter a string and a number, fill the string in the inverted Z-input string, and then read the character by column, and get a new character that prints the character. Example: string "Paypalishiring", 3

p< /td>	&NBSP;	a		h	&NBSP;	n
a	p	l	s	i	i	g
y	&NBSP;	i	&NBSP;	r	&NBSP;	&NBSP;

The new character obtained is "Pahnaplsiigyir".

Topic Ideas:

This problem is just a simple string processing. First, we can simply optimize the z-string to combine the "fold" in Z. For example: "ABCDEFGHIJKL", 4

/tr> tr>

a	 	& nbsp;	g	 	 
b	 	f	h	 	l
c	e	 	i	k	 
d	&NBSP;		j	&NBSP;	< /td>

After optimization:

A		G
B	F	H	L
C	E	I	K
D		J

It is not difficult to find that the resulting results are the same, and the number of columns in the list is reduced. In C and C + +, you can directly define a two-dimensional array, read the characters in, and then read directly. But with the Python initialization list is troublesome, I think directly through the subscript rule can be directly obtained, the first line and the last line next subscript is the previous + 2*numrows–2, while the other is First + (numrows-i) –2 + 2*i,i is the number of lines.

Code (Python):

1 classsolution (object):2     defconvert (self, S, numrows):3         """4 : Type S:str5 : Type Numrows:int6 : Rtype:str7         """8Size =Len (s)9         ifSize <= NumRowsorNumRows = = 1:Ten             returns OneAns ="' Ai =0 -          whileI <NumRows: -j =I the             ifi = = 0ori = = NumRows-1: -                  whileJ <Size: -Ans + =S[j] -J + = 2*numrows-2 +                     if2 * NumRows-2 = =0: -                          Break +             Else: A                  whileJ <Size: atAns + =S[j] -J + = (numrows-i)-2 -                     ifJ >=Size: -                          Break -Ans + =S[j] -J + =I ini + = 1 -         returnAns

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Reprint Please specify source: http://www.cnblogs.com/chruny/p/4798575.html

[Leetcode] (python): 006-zigzag Conversion