LeetCode 6 ZigZag Conversion 模拟 难度:0

https://leetcode.com/problems/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   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".

class Solution {
public:
    string convert(string s, int numRows) {
        if(numRows == 1)return s;
        string* a = new string[numRows];
        string ans;
        int n = 2 * numRows - 2;
        for(int i = 0;i < s.size();i++)
        {
            int r = i % n;
            int l = r % numRows;
            if(l == r)a[l] += s[i];
            else a[numRows - l - 2] += s[i];
        }
        for(int i = 0;i < numRows;i++){
            ans += a[i];
        }
        return ans;
    }
};