59. Spiral Matrix II

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

For example,
Given n = 3,

You should return the following matrix:

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

思路：跟spiral matrix的想法一样。只是把right,bottom换成n-1。不是很清楚if条件是不是需要。我觉得是需要的，不同的n终止的地方不一样。。。

public class Solution {
    public int[][] generateMatrix(int n) {
        int[][] matrix=new int[n][n];
        int total=n*n;
        int left=0,top=0,right=n-1,bottom=n-1;
        int number=1;
        while(number<=total)
        {
        for(int i=left;i<=right;i++)
        {
            matrix[top][i]=number;
            number++;
        }
        top++;
        if(top>bottom)
        {
            break;
        }
        for(int j=top;j<=bottom;j++)
        {
            matrix[j][right]=number;
            number++;
        }
        right--;
        if(right<left)
        {
            break;
        }
        for(int k=right;k>=left;k--)
        {
           matrix[bottom][k]=number;
           number++;
        }
        bottom--;
        if(bottom<top)
        {
            break;
        }
        for(int m=bottom;m>=top;m--)
        {
            matrix[m][left]=number;
            number++;
        }
        left++;
        
        }
        return matrix;
        
    }
}