6.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   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".

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思路：用nRow个子容器，按照Z形顺序分别读取字符到各个子容器中，最后将各个子容器拼接起来即可。

代码：

class Solution {
public:
    string convert(string s, int nRows) {
        //判错
        if(nRows<=0) return NULL;
        if(nRows==1) return s;
        int len=s.size();
        if(len==0) return "";
        
        string *sub_s=new string[nRows];
        for(int i=0;i<nRows;++i){
            sub_s[i]="";
        }
        int count=0;
        int phase_count=0;
        
        while((count<len)){
            while((count<len)&&(phase_count<nRows)){
                sub_s[phase_count++]+=s[count++];
            }
            phase_count-=2;
            while((count<len)&&(phase_count>0)){
                sub_s[phase_count--]+=s[count++];
            }
        }
        
        string tem_s;
        for(int i=0;i<nRows;++i){
            tem_s+=sub_s[i];
        }
        delete []sub_s;
        return tem_s;
    }
};