LeetCode之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].

#include 
class Solution {
public:
	vector spiralOrder(vector> &matrix) {
		vector result;
		if (matrix.size() == 0) return result;
		int rowB = 0, rowE = matrix.size()-1;
		int columnB = 0, columnE = matrix[0].size()-1;
		while(true){
			//left->right
			for (int i = columnB; i <= columnE; i++)
				result.push_back(matrix[rowB][i]);
			if (++rowB > rowE)
				break;

			//top->bottom
			for (int i = rowB; i <= rowE; i++)
				result.push_back(matrix[i][columnE]);
			if (--columnE < columnB)
				break;

			//right->left
			for (int i = columnE; i >= columnB; i--)
				result.push_back(matrix[rowE][i]);
			if (--rowE < rowB)
				break;

			//bottom->top
			for (int i = rowE; i >= rowB; i--)
				result.push_back(matrix[i][columnB]);
			if (++columnB > columnE)
				break;	
		}//while
		return result;
	}
};