59. Spiral Matrix II(中等，同54题)

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

For example,
Given n = 3,
You should return the following matrix:

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

思路完全同 54. Spiral Matrix(中等).
自个代码：

vector<vector<int>> generateMatrix(int n) {
	vector<vector<int>> A(n, vector<int>(n)); //n行n列,动态的

	// Normal Case
	int rowStart = 0;
	int rowEnd = n - 1;
	int colStart = 0;
	int colEnd = n - 1;
	int num = 1; //change

	while (rowStart <= rowEnd && colStart <= colEnd) {
		for (int i = colStart; i <= colEnd; i++) {
			A[rowStart][i] = num++; //change
		}
		rowStart++;

		for (int i = rowStart; i <= rowEnd; i++) {
			A[i][colEnd] = num++; //change
		}
		colEnd--;

		for (int i = colEnd; i >= colStart; i--) {
			if (rowStart <= rowEnd)
				A[rowEnd][i] = num++; //change
		}
		rowEnd--;

		for (int i = rowEnd; i >= rowStart; i--) {
			if (colStart <= colEnd)
				A[i][colStart] = num++; //change
		}
		colStart++;
	}
	return A;
}