ZigZag Conversion题目及解法

问题描述:

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" .


大致思路,用空间换时间,看每一个字母放第几行,用step控制行数,当遍历完s时,把每一行的字符串连接起来即可得到答案。

代码如下:

if (numRows <= 1)
        return s;

	    const int len = (int)s.length();
	    string *str = new string[numRows];
	
	    int row = 0, step = 1;
	    for (int i = 0; i < len; ++i)
	    {
	        str[row].push_back(s[i]);
	
	        if (row == 0)
	            step = 1;
	        else if (row == numRows - 1)
	            step = -1;
	
	        row += step;
	    }
	
	    s.clear();
	    for (int j = 0; j < numRows; ++j)
	    {
	        s.append(str[j]);
	    }
	
	    delete[] str;
	    return s;	

欢迎大家交流~~

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