HackerHeap

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

Example:

Input: 3
Output:
[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]

Solution 1:

class Solution {
    public int[][] generateMatrix(int num) {
        int[][] spiralMatrix = new int[num][num];
        int m = num;
        int n = num;
        int i =0;
        int j = 0;
        int k;
        int number  = 1;
        while(j<n && i<m){
            
            for( k=j;k<n;k++){
                spiralMatrix[i][k] = number;
                number++;
                //System.out.println(spiralMatrix[i][k]+" "+i+" "+k);
            }
            i++;
            for( k = i;k<m;k++){
                spiralMatrix[k][n-1] = number;
                number++;
                             //   System.out.println(spiralMatrix[k][n-1]+" "+k+" "+(n-1));

            }
            n--;
            if(i<m){
                for( k = n-1; k>=j;--k){
                    spiralMatrix[m-1][k] = number;
                    number++;
                   // System.out.println(spiralMatrix[m-1][k]+" "+(m-1)+" "+k);
                }
                m--;
            }
            
            if(j<n){
                for( k= m-1;k>=i;--k){
                    spiralMatrix[k][j] = number;
                    number++;
                }
                j++;
            }
        }
        return spiralMatrix;
    }
}