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”.

題目意思就是在首尾行中間徘徊著寫字母。設定一個字串陣列。陣列的元素個數就是行數。最後把每一行都拼接起來。
程式碼如下：

    string convert(string s, int numRows) {
        if(numRows<=1) return s;//注意只有1行時無法滿足下面的for迴圈的。
        string res[numRows];
        int
 
 step=1;
        int row=0;
        for(int i=0;i<s.size();i++){
            if(row==0) step=1;
            if(row==numRows-1) step=-1;
            res[row]+=s[i];
            row=row+step;
        }
        for(int i=1;i<numRows;i++){
            res[0]+=res[i];
        }
        return res[0];
    }