N-shaped shift direction change flag tag

topic:

The number of a given string according to the given row, to down, left to right from the Z-shaped arrangement.

Example, the input string is the number of rows "LEETCODEISHIRING" is 3, arranged as follows:

LCIR
ETOESIIG
EDHN
After that, you need the output from left to right read line by line, produce a new string, such as: "LCIRETOESIIGEDHN".

You will realize this string conversion function specified number of lines:

string convert (string s, int numRows );
Example 1:

Input: s = "LEETCODEISHIRING", numRows = 3
Output: "LCIRETOESIIGEDHN"
Example 2:

Input: s = "LEETCODEISHIRING", numRows = 4
Output: "LDREOEIIECIHNTSG"
explanation:

L D R
E O E I I
E C I H N
T S G

 

 

 

/**
 * @param {string} s
 * @param {number} numRows
 * @return {string}
 */
var convert = function(s, numRows) {
    if(numRows<2){
        return s;
    }
   let str = new Array();
    for(let i=0;i<numRows;i++){
        str[i] = "";
    }
    let index =0;
    let flag = -1;
    let j=0;
    while(index<s.length){
        str[j]+= s[index];
        index ++;
        if(j==0|| j==numRows-1){
            flag = -flag;
        }
        j +=flag;
    }
    
    return str.join("")
        
};

Ways: primarily through the use of a flag array direction and converting the character string into the array corresponding traverse into, and finally merge array

Source: https://leetcode-cn.com/problems/zigzag-conversion/solution/zzi-xing-bian-huan-by-jyd/

Source: stay button (LeetCode)
link: https: //leetcode-cn.com/problems/zigzag-conversion
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