LeetCode 59 _ Sprial Matrix II 旋转矩阵2

Description:

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

Example:

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

 

 

Solution：

这道题和那道：LeetCode 54 _ Sprial Matrix 旋转矩阵 是一样的，思路也完全相似，就不赘述了。

有一点相比于LC54中写的可以优化的是，由于这次输入的col和row相同，我们可以直接通过已经输出的字符数直接判断是否输入完成，这样就不用在每回第三、四次转向的时候继续判断是否越界了。

 

 

Code:

public int[][] generateMatrix(int n) {
	int[][] res = new int[n][n];

	if (n == 0) {
		return res;
	}

	int count = 1;
	int rowS = 0, rowE = n - 1;
	int colS = 0, colE = n - 1;

	while (count <= n * n) {
		for (int i = colS; i <= colE; i++) {
			res[rowS][i] = count;
			count++;
		}
		rowS++;

		for (int i = rowS; i <= rowE; i++) {
			res[i][colE] = count;
			count++;
		}
		colE--;

		for (int i = colE; i >= colS; i--) {
			res[rowE][i] = count;
			count++;
		}
		rowE--;

		for (int i = rowE; i >= rowS; i--) {
			res[i][colS] = count;
			count++;
		}
		colS++;
	}
	return res;
}

　　

 

提交情况:

 第一次啊！一次提交100%！纪念一下：