https://leetcode.com/problems/zigzag-conversion/description/
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”.
答案
每行是一个StringBuilder,先垂直向下转换,再斜向上转换。1
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15 public static String convert(String s, int numRows) {
int len = s.length();
char[] c = s.toCharArray();
StringBuilder[] sb = new StringBuilder[len];
for (int i = 0; i < numRows && i < len; i++) sb[i] = new StringBuilder();
int i = 0;
while (i < len) {
for (int j = 0; j < numRows && i < len; j++) sb[j].append(c[i++]);//垂直向下
for (int j = numRows - 2; j > 0 && i < len; j--) sb[j].append(c[i++]);
//斜向上
}
StringBuilder res = new StringBuilder();
for (int k = 0; k < numRows && k < len; k++) res.append(sb[k]);
return res.toString();
}