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: "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".

 1 class Solution {
 2 public:
 3     string convert(string s, int nRows) {
 4         if(nRows == 1)
 5             return s;
 6         string res;
 7         int step = (nRows - 1) * 2;
 8         int N = s.size();
 9         
10         for(int i = 0; i < nRows; i++) {
11             int j = 0;
12             while(1) {
13                 if(i > 0 && i < nRows-1 && j-i >= 0 && j-i < N)
14                     res.push_back(s[j-i]);
15                 if(i+j < N) 
16                     res.push_back(s[j+i]);
17                 if(i+j >= N) break;
18                 j += step;
19             }
20         }
21         return res;
22     }
23 };

 

posted @ 2014-04-22 04:57  beehard  阅读(187)  评论(0)    收藏  举报