LeetCode 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".

answer:

class Solution {public:    string convert(string s, int numRows) {        string* blacket = new string[numRows * 2];        string result = "";        int index = 0;        bool flag = false;        if(numRows == 1)            return s;        for(int i = 0; i < s.length(); i ++){            if(!flag && (index < numRows)){                blacket[index ++] += s[i];            }            else if(index == numRows){                index -= 2;                flag = true;            }            if(flag){                if(index > 0){                    blacket[index --] += s[i];                }                else{                    blacket[index ++] += s[i];                    flag = false;                }             }        }        for(int i = 0; i < numRows * 2; i ++){            result += blacket[i];        }        delete[] blacket;        return result;    }};