[Leetcode] 6. ZigZag Conversion

解题思路 ：
之字型打印
蓝色为 垂直向下 x++
绿色为 东北方向 x--, y ++

image.png

/*
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 s, int numRows);
Example 1:

Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"
Example 2:

Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:

P     I    N
A   L S  I G
Y A   H R
P     I
*/

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

class Solution
{
  public:
    string convert(string s, int numRows)
    {

        if (s == "" || numRows == 0)
        {
            return "";
        }

        if (numRows == 1)
        {
            return s;
        }

        const int row = numRows;
        const int col = s.size();
        char mat[row][col];
        for (int i = 0; i < row; i++)
        {
            for (int j = 0; j < col; j++)
            {
                mat[i][j] = '0';
            }
        }
        
        int count = 0;
        int i = 0;
        int j = 0;

        while (count < s.size())
        {

            for (int x = 0; x < row && count < s.size(); x++)
            {
                mat[x][j] = s[count++];
            }

            for (int x = row - 2; x >= 1 && count < s.size(); x--)
            {
                mat[x][++j] = s[count++];
            }
            j++;
        }



        for (int i = 0; i < row; i++)
        {
            for (int j = 0; j < col; j++)
            {
                cout << mat[i][j] << ' ';
            }
            cout << '\n';
        }
        string ans = "";

        for (int i = 0; i < row; i++)
        {
            for (int j = 0; j < col; j++)
            {
                if (mat[i][j] != '0')
                {
                    ans += mat[i][j];
                }
            }
        }

        return ans;
    }
};

int main()
{
    Solution s;
    string str = "ABCDEFGHIGKSDJKJS";
    int nums = 4;
    cout << s.convert(str, nums) << endl;
    return 0;
}

输出：

kevifunaudeMacBook-Pro:leetcode fmb$ ./a.out
A 0 0 G 0 0 D 0 0 0 0 0 0 0 0 0 0
B 0 F H 0 S J 0 0 0 0 0 0 0 0 0 0
C E 0 I K 0 K S 0 0 0 0 0 0 0 0 0
D 0 0 G 0 0 J 0 0 0 0 0 0 0 0 0 0
AGDBFHSJCEIKKSDGJ

然而速度很慢 -_-

image.png

应该 可以把矩阵优化一下，懒 不想动。。