[leetcode] ZigZag Conversion

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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   NA P L S I I GY   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".

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

思路：找規律。每個zigzag是2*rows-1個字元。

public class Solution {public String convert(String s, int nRows) {if (nRows == 1)return s;StringBuilder sb = new StringBuilder();int len = s.length();for (int i = 0; i < nRows; i++) {if (i == 0 || i == nRows - 1) {int j = i;while (j < len) {sb.append(s.charAt(j));j += 2 * nRows - 2;}} else {int j = i;int k = 2 * nRows - 2 - i;while (j < len || k < len) {if (j < len)sb.append(s.charAt(j));if (k < len)sb.append(s.charAt(k));j += 2 * nRows - 2;k += 2 * nRows - 2;}}}return sb.toString();}public static void main(String[] args) {System.out.println(new Solution().convert("PAYPALISHIRING", 3));System.out.println(new Solution().convert("abcdefghijklmn", 5));System.out.println(new Solution().convert("abcdefghijklmn", 4));System.out.println(new Solution().convert("abcdefghijklmn", 1));}}

 

 

 

 

參考：

http://fisherlei.blogspot.com/2013/01/leetcode-zigzag-conversion.html

http://blog.csdn.net/linhuanmars/article/details/21145039