leetcode 6. 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".

ZigZag conversion 解題關鍵點在於尋找迴圈，（2 * nRows - 2）個字元構成一個迴圈。

 1     string convert(string s, int nRows)  2     { 3         string *st = new string[nRows]; 4         int k, i; 5         if (nRows <= 1) 6             return s; 7              8         for (i = 0; i < s.length(); i++) 9         {10             k = i % (2 * nRows - 2);11             if (k >= (nRows - 1))12                 st[2 * (nRows - 1) - k] += s[i];13             else14                 st[k] += s[i];15         }16         17         s = "";18         for (i = 0; i < nRows; i++)19             s += st[i];20             21         return s;22     }

 

leetcode 6. ZigZag Conversion