LeetCode 6. ZigZag Conversion

最新推荐文章于 2021-03-20 20:07:40 发布

原创最新推荐文章于 2021-03-20 20:07:40 发布 · 171 阅读

0 ·

CC 4.0 BY-SA版权

数据结构和算法专栏收录该内容

90 篇文章

订阅专栏

本文介绍了一种将字符串以Z字形方式分布在多行上的算法，并提供了完整的Java代码实现。该算法通过调整行数和字符位置来实现字符串的转换。

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" .

Subscribe to see which companies asked this question.

Z字型打印。

public class Solution {
    public String convert(String s, int numRows) {
        int len = s.length();
        if (len<=numRows||numRows==1){
            return s;
        }
        int f = 0;
        StringBuilder ans = new StringBuilder();
        for(int j=0;j<numRows;j++){
            int l = 0;
            for(int i=j;i<len;i+=(f==0?2*(numRows-j-1):2*j)){
                ans.append(s.charAt(i)); 
                if(j!=0&&j!=numRows-1){
                    f = 1 - f;
                }
                if(l==0){
                    f = 0;
                    l = 1;
                }
                if(j==numRows-1){
                    f = 1;
                    l = 1;
                }
                if(ans.length()==s.length()){
                    break;
                }
            }
        }
        return ans.toString();
    }
}

tips：一定记得用StringBuilder！相同的程序，使用String耗时128ms，stringbuilder加速一倍以上