ZigZag Conversion

最新推荐文章于 2025-05-22 17:48:42 发布

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本文介绍了如何将给定的字符串通过zigzag模式转换并读取，并提供了相应的代码实现。重点在于理解每行中字符之间的关系及特殊条件的处理。

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".

Have you been asked this question in an interview?
这道题目最主要的是清楚在每一行中，第一个数和第二个数的关系，写关系式的时候小心不要出错
另外在开始的时候要判断 nRows == 1 时直接输出，否则会 time limited exceeded

public class Solution {
    public String convert(String s, int nRows) {
        if (s == null || s.length() == 0 || nRows == 1) {
            return s;
        }
        int l = s.length();
        StringBuilder res = new StringBuilder();
        for (int row = 1; row <= nRows; row ++) {
            int i = row - 1;
            if (row == 1 || row == nRows) {
                while (i < l) {
                    res.append(s.charAt(i));
                    i+= (2*nRows - 2);
                }
            } else {
                while (i < l) {
                    res.append(s.charAt(i));
                    if ( (i + 2* nRows - 2* row ) < l) {
                        res.append(s.charAt(i + 2*nRows - 2*row));
                        i+= (2*nRows - 2);
                    } else {
                        break;
                    }
                }
            }
        }
        return res.toString();
    }
}