【leetcode】第6题 ZigZag Conversion 题目+解析+代码

【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   NA P L S I I GY   I   RAnd 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".

【解析】

这道题主要是不知道ZigZag的意思。ZigZag就是将原字符串按照这样一种顺序书写。

所以我想的是找每行的字母之间的间隔。每竖行之间周期为2*numRows-2，除了首末行，中间行还要加斜着的，距离为2*numRows-2i

【代码】

public class Solution {    public String convert(String s, int numRows) {        int length=s.length();        if(length<2||numRows==1){            return s;        }        char[] str=new char[length];        int count=0;        int i=0,j=0;        while(i<length){            str[count]=s.charAt(i);            i=i+2*numRows-2;            count++;        }        for(i=2;i<numRows;i++){            j=i-1;            while(j<length){                str[count]=s.charAt(j);                count++;                j=j+2*numRows-2*i;                if(j<length){                    str[count]=s.charAt(j);                    count++;                }                j=j+2*(i-1);            }        }        i=numRows-1;         while(i<length){            str[count]=s.charAt(i);            i=i+2*numRows-2;            count++;        }       return String.valueOf(str);     }}