LeetCode | 6)ZigZag Conversion

题目

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”

prototype

class Solution {
public:
    string convert(string s, int numRows) {

};

代码

class Solution {
public:
    string convert(string s, int numRows) {
        string res;
        vector<string> vstr(numRows);
        if (numRows == 1)   return s;
        int i{0}, n{0};
        while (i < s.size())
        {
            while (i < s.size() && n < numRows - 1)
            {
                vstr[n++] += s[i++];
            }
            while (i < s.size() && n > 0)
            {
                vstr[n--] += s[i++];
            }
        }
        for (auto &p : vstr)
            res += p;
        return res;
    }
};