20210725-Z字形变换

Z字形变换
题目链接：https://leetcode-cn.com/problems/zigzag-conversion/

思路：纯找规律，本质上每一行的字母在原字符串中的序号取余都会呈现一定的pattern。

参考代码：

class Solution {
public:
    string convert(string s, int numRows) {
        if (numRows < 1) {
            return "";
        }
        string res;
        int loop = numRows * 2 - 2;
        int gap = loop - 2;
        for (int i = 0; i < s.size(); i += loop) {
            res += s[i];
        }
        for (int i = 1; i < numRows - 1; ++i) {
            for (int j = i; j < s.size(); j += loop) {
                res += s[j];
                res += s[j + gap];
            }
            gap -= 2;
        }
        for (int i = numRows - 1; i < s.size(); i += loop) {
            res += s[i];
        }
        return res;
    }
};