leetcode143zigzag-conversion

题目描述

字符串"PAYPALISHIRING"写成3行的Z字形的样式如下：

P   A   H   N↵A P L S I I G↵Y   I   R

按行读这个Z字形图案应该是 "PAHNAPLSIIGYIR"

请编写代码完成将字符串转化为指定行数的Z字形字符串：

string convert(string text, int nRows);

convert("PAYPALISHIRING", 3)应该返回"PAHNAPLSIIGYIR"

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"

示例1

输入

复制

"AB",2

输出

复制

"AB"
class Solution {
public:
    /**
     * 
     * @param s string字符串 
     * @param nRows int整型 
     * @return string字符串
     */
    string convert(string s, int nRows) {
        // write code here
        if (nRows <=1) return s;
        int t=nRows+nRows -2;//求出循环周期
        string res="";
        vector <string> m(nRows,res);
        for (int i=0;i<s.length();i++){
            int a=i%t;
            if (a<nRows)//往下走
                m[a]+=s[i];
            else 
                m[t-a]+=s[i];//往上走
            
        }
        for (int i=0;i<nRows;i++)
            res+=m[i];
        return res;
        
        
    }
};