6.ZigZag Conversion(Graph, traverse)

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".

 

思路：图的遍历，先纵向，再横向。图用string数组存储

class Solution {

public:

    string convert(string s, int numRows) {

        string sArray[numRows];

        int pChar = 0; //pointer to s

        int pRow = 0; //pointer to indicate row number

        

        while(1){

            pRow = 0;

            while(pRow < numRows && pChar != s.length()){ //traverse first colomn

              sArray[pRow++] += s[pChar++];

            }

            if(pChar == s.length()) return getReturnStr(sArray,numRows);

         

            pRow = numRows-2;

            while(pRow > 0 && pChar != s.length()){

              sArray[pRow--] += s[pChar++];

            }

            if(pChar == s.length()) return getReturnStr(sArray,numRows);

        }

    }

    string getReturnStr(string* sArray, int numRows){

        string ret = "";

        for(int i = 0; i < numRows; i++){

            ret += sArray[i];

        }

        return ret;

    }

};