Spiral Matrix II

最新推荐文章于 2025-01-09 18:09:55 发布

最新推荐文章于 2025-01-09 18:09:55 发布 · 58 阅读

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本文介绍了一个生成螺旋矩阵的算法，该算法接收一个整数n作为输入，并返回一个n×n的螺旋矩阵。矩阵中填充了从1到n²的元素，按螺旋顺序排列。文章通过一个具体的例子展示了算法的工作原理，并提供了详细的Java实现代码。

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 ]
]

public class Solution {
	public int[][] generateMatrix(int n) {
		int[][] res = new int[n][n];
		int cnt = 1;
		int top = 0;
		int bottom = n - 1;
		int left = 0;
		int right = n - 1;
		while (left < right && top < bottom) {
			for (int i = left; i < right; i++) {
				res[top][i] = cnt++;
			}
			for (int i = top; i < bottom; i++) {
				res[i][right] = cnt++;
			}
			for (int i = right; i > left; i--) {
				res[bottom][i] = cnt++;
			}
			for (int i = bottom; i > top; i--) {
				res[i][left] = cnt++;
			}
			left++;
			right--;
			top++;
			bottom--;
		}
		if (n % 2 != 0) {
			res[n/2][n/2] = cnt;
		}
		return res;
	}
}