【LeetCode】Spiral Matrix

Spiral Matrix

 

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

For example,
Given the following matrix:

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

You should return [1,2,3,6,9,8,7,4,5].

public class Solution {
    public ArrayList<Integer> spiralOrder(int[][] matrix) {
        ArrayList<Integer> re = new ArrayList<Integer>();
        
        if(matrix.length==0)
            return re;
        
        
        int row = matrix.length;
        int col = matrix[0].length;
        
        int start=-1;
        int end=-1;
        int temprow=row;
        int tempcol = col;
        
        while(temprow>0&&tempcol>0){
            start++;
            end++;
            //如果剩下的行数或者列数位0
            if(temprow==start||tempcol==end)
                break;
            for(int i=start;i<tempcol;i++)
                re.add(matrix[start][i]);
            for(int j=start+1;j<temprow;j++)
                re.add(matrix[j][tempcol-1]);
            
            //如果剩余一行或者一列
            if((temprow-1)==start||(tempcol-1)==end)
                break;
            for(int x=tempcol-2;x>=end;x--)
                re.add(matrix[temprow-1][x]);
            for(int y=temprow-2;y>start;y--)
                re.add(matrix[y][end]);
            
            temprow=temprow-1;
            tempcol=tempcol-1;
        }
        return re;
        
    }
}