Leetcode ZigZag Conversion C + + problem solving ideas

A difficult problem for easy, see a lot of people's problems are not trying to understand, and finally hard to think hard, just think about the same. It's too weak to find a job.

Title Description:

The string is "PAYPALISHIRING" written with 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   NA p L S i i GY   i   R

And then read on line:"PAHNAPLSIIGYIR"

Write the code that would take a string and make this conversion given a number of rows:

String convert (string text, int nRows);

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

n=2

0 2 4 6

1 3 5 7

N=3

0 4 8

1 3 5) 7 9

2 6 10

N=4 the way to go is:

0 6 12

1 5 7) 11 13

2 4 8) 10 14

3 9 15

The problem is to find a regular problem.

Analyze the rules of each line and then piece together.

A closer look reveals that a vertical column and a diagonal column are a period, with a period of 2n-2,n being the number of rows. A vertical column has n elements, the first row and the last row have no elements so it is n-2 elements, so the add-up period is 2n-2 elements. The distance difference between the elements on each row adjacent to the vertical column is a period, for example, when n=4, the period is 2*4-2 = 6, the element 0 and 6 are 6, the elements 1 and 7 differ by 6.

In each row in the middle, there is an oblique element in the middle of each of the two vertical columns, for example, 1 and 7 are 5,7 and 13 in the middle is 11. The middle oblique element differs from the element on the previous vertical column to a period of -2* row index. As can be understood, for example, when n=4, the element of the next period of 2 is 8, then 2 and 4 distance is 2 to 8 distance minus 4 to 8 distance, 2 to 8 distance is a period, 4 to 8 is 1+2+2+......+1, the first 1 is the element of the No. 0 row, The last 1 is the element (that is, 8) of the current row (line I), with two elements in the middle of each row, since I start with 0, so there is a total of I 2. So the distance from 2 to 4 is 2n-2-2i, if the position of 2 is J, then the position of 4 is j+2n-2-2i,8 position is j+2n-2.

The code is as follows:

stringConvertstringSintnRows) {    if(s.length () = =0|| nrows<=0)        return ""; if(NRows = =1)        returns; stringRes; intSize =2*nrows-2;  for(inti =0; i < nRows; i++)         for(intj = i; J <s.length (); j+=size) {Res+=S[j]; if(i!=0&& I! = nrows-1){                inttemp = j+size-2*i; if(Temp <s.size ()) Res+=S[temp]; }        }    returnRes; }

REF:[1]. Http://www.cnblogs.com/springfor/p/3889414.html

[2].http://blog.unieagle.net/2012/11/08/leetcode%e9%a2%98%e7%9b%ae%ef%bc%9azigzag-conversion/

Leetcode ZigZag Conversion C + + problem solving ideas