LeetCode -- Spiral Matrix II

LeetCode -- Spiral Matrix II
Description:


Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.


For example,
Given n = 3,


You shoshould return the following matrix:
[
[1, 2, 3],
[8, 9, 4],
[7, 6, 5]
]


Given a number, the matrix is generated from the external to the internal.


Ideas:


This topic is mainly to complete a rotating process. The width of the track cycle is divided into four different directions: left-to-right, top-to-bottom, right-to-left, and left-to-top. Cycle decreases every time.
Pay attention to the difference in cycle values where n is an odd and even number.




Implementation Code:

public class Solution {    public int[,] GenerateMatrix(int n) {        var matrix = new int[n,n];    var row = n % 2 == 0 ? n / 2 : (n+1) / 2;    var count = 1;    for(var cycle = 0;cycle < row; cycle++){        // left to right    for(var col = cycle;col < n - cycle - 1; col++){    matrix[cycle,col] = count ++;    }        // right to bottom    for(var r = cycle ; r < n - cycle; r++){    matrix[r, n - cycle - 1] = count ++;    }        // bottom to left    for(var col = n - cycle - 2;col >= cycle; col --){    matrix[n-cycle-1,col] = count ++;    }        // left to top    for(var r = n - cycle - 2;r > cycle; r --){    matrix[r,cycle] = count ++;    }    }        return matrix;    }}