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)



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”.

分析

思路参考博客，在此表示对博主的感谢。

向下循环:nRows

斜角线循环:nRows-2(减去首尾两个端点)

重复

…

AC代码

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

        if (s.empty() || numRows == 1)
            return s;
        //声明numRows个字符串，对该之字型序列处理
        string *res = new string[numRows];
        int i = 0, j, gap = numRows - 2;
        while (i < s.size()){
            for (j = 0; i < s.size() && j < numRows; ++j) res[j] += s[i++];
            for (j = gap; i < s.size() && j > 0; --j) res[j] += s[i++];
        }
        string str = "";
        for (i = 0; i < numRows; ++i)
            str += res[i];
        return str;
    }

};

GitHub测试程序源码