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  • ZigZag Conversion

    1. Question

    给定行数,将某字符串转换为zigzag形式,然后按行输出。zigzag形式如:

    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".

     2. Solution

    O(n),遍历每个字符,依次将其加入第m行的字符串中,最后将所有行的字符串组合起来

    public class Solution {
        public String convert( String s, int nRows ){
            if( nRows == 1 )    return s;
            StringBuilder[] res = new StringBuilder[nRows];
            for( int i=0; i<nRows; i++ )
                res[i] = new StringBuilder();
            int loop = 2 * nRows-2;
            int mid = nRows-1;
            for( int i=0; i<s.length(); i++ )
                res[ mid - Math.abs( i % loop - mid ) ].append(s.charAt(i));
            for( int i = 1; i<nRows; i++ )
                res[0].append( res[i] );
            return res[0].toString();
        }
    }
    View Code
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  • 原文地址:https://www.cnblogs.com/hf-cherish/p/4572772.html
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