LeetCode——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   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"

.

字符串的弯曲转换。

要做的首先就是发现每一行的规律，能够发现，每一行有2 * nRows - 2个字符。把结果的列先增加到新的字符串中。再增加行。

public String convert(String s, int nRows) {
if(nRows <= 1)
return s;
StringBuffer buf = new StringBuffer();
int period = 2 * nRows - 2;
for(int i=0;i<nRows;i++){
for(int j=i;j<s.length();j+=period){
buf.append(s.charAt(j));
if(i !=0 && i != nRows - 1 && j+period - 2*i <s.length())
buf.append(s.charAt(j+period - 2*i));
}
}
return buf.toString();
}