LeetCode 6. 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".

 

思路：

1.每个‘n’就是一个循环，位置都是可以计算出来的

2.用一个flag来记录位置，通过改变step =1 OR step = -1来更改方向

 

代码：C++  思路1:

class Solution {
public:
    string convert(string s, int numRows) {
        if (numRows == 1)
            return s;
        
        vector<string> str (numRows,"");
        string solve = "";
        int row = 0;        
        int row_max = numRows - 1;
        int mod = 2 * numRows - 2;
        
        for (int i = 0; i < s.length(); i++) {
            row = row_max - abs(i % mod - row_max);
            str[row] += s[i];
        }
        
        for (int i = 0; i < numRows; i++) {
            solve += str[i];
        }
        return solve;
    }
};