p6

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LeetCode p6 ZigZag Conversion 题解

1.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)

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”.

题意：

输入一个字符串，和一个行数，将字符串如上Z字型排列，输出排列后的字符串。

2.解题思路:

见代码

3.代码

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public class Solution {
    public String convert(String s, int numRows) {
        if (s.length() <= numRows)
			return s;
		char[] c = s.toCharArray();
		StringBuilder[] slist = new StringBuilder[numRows];
		for (int i = 0; i < numRows; i++)
			slist[i] = new StringBuilder();
		for (int i = 0; i < c.length;) {
			// down
			for (int j = 0; j < numRows && i < c.length; j++, i++) {
				slist[j].append(c[i]);
			}
			// up
			for (int j = numRows - 2; j > 0 && i < c.length; j--, i++) {
				slist[j].append(c[i]);
			}
		}
		StringBuilder sBuilder = new StringBuilder();
		for (int i = 0; i < numRows; i++) {
			sBuilder.append(slist[i].toString());
		}
		return sBuilder.toString();
    }
}

4.一些总结：