ZigZag Conversion(LeetCode)

文章目录

1. 1. Question:ZigZag Conversion
2. 2. SourceCode:
   1. 2.1. s1
   2. 2.2. s2

Question: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".

SourceCode:

s1

//笔者提交版本；耗时：6ms；
public class Solution {
    public String convert(String s, int numRows) {
        
        if(null == s){return "";}
        
        int len = s.length();
        
        //边界控制要仔细啊，numRows <=1 
        if(numRows >= len||numRows <=1){return s;}
        
        StringBuilder result = new StringBuilder(len);
        int step = numRows - 2 + numRows;
        int lastLineNum = numRows -1 ;
        
        for(int i= 0 ; i< numRows ;i++){
            //第一行和最后一行
            if(i==0 || i == lastLineNum){
                int j = i;
                while(j<len){
                    result.append(s.charAt(j));
                    j += step;
                }
            }
            //中间行处理
            else{
                int tmpStep = (lastLineNum-i)*2;
                //成对处理
                int j = i;
                int k = j + tmpStep;
                while(j<len){
                    result.append(s.charAt(j));
                    j += step;
                    if(k<len){
                        result.append(s.charAt(k));
                        k += step;
                    }
                    
                }
            }
        }
        
        return result.toString();
    }
}

s2

//该版本参考了Discuss,还没看Discuss；耗时：ms；
//待写