Spiral Matrix II

Source

• lintcode: Spiral Matrix II

Given an integer n, generate a square matrix filled with elements from 1 to n^2 in 
spiral order.

Example
Given n = 3,

You should return the following matrix:

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

Java

public class Solution {
    /**
     * @param n an integer
     * @return a square matrix
     */
    public int[][] generateMatrix(int n) {
        int[][] result = new int[n][n];
        int start=0;
        int end=n-1;
        int count=1;

        while(start<end){

            for(int i=start; i<end; i++){
                result[start][i]=count;
                count++;
            }

            for(int i=start; i<end; i++){
                result[i][end]=count;
                count++;
            }

            for(int i=end; i>start; i--){
                result[end][i]=count;
                count++;
            }

            for(int i=end; i>start; i--){
                result[i][start]=count;
                count++;
            }
            start++;
            end--;
        }

        if(start==end){
            result[start][end]=count;
        }

        return result;
    }
}

Python

class Solution:
    # @param {int} n an integer
    # @return {int[][]} a square matrix
    def generateMatrix(self, n):
        # Write your code here
        result=[[0 for x in range(n)] for x in range(n)]
        start=0
        end=n-1;
        count=1

        while start<end:
            for i in range(start, end):
                result[start][i] = count
                count+=1

            for i in range(start, end):
                result[i][end] = count
                count+=1

            for i in range(end, start, -1):
                result[end][i] = count
                count+=1

            for i in range(end, start, -1):
                result[i][start] = count
                count+=1

            start+=1
            end-=1

        if start==end:
            result[start][end]=count

        return result