题目：
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".
代码：
class Solution { public: string convert(string s, int numRows) { const int len = s.size(); if ( len<numRows || numRows==1 ) return s; vector<char> ret; const int INTERVAL = 2*numRows-2; for ( int i=0; i<numRows; ++i ) { int interval = 2*(numRows-i)-2; for ( int j=i; j<len; interval=INTERVAL-interval) { ret.push_back(s[j]); j = (interval==INTERVAL||interval==0) ? j+INTERVAL : j+interval; } } return string(ret.begin(),ret.end()); } };
tips：
找到ZigZag每行元素在元字符串s中间隔大小的规律。
原文：http://www.cnblogs.com/xbf9xbf/p/4562639.html