螺旋矩阵-ii

题目

给你一个正整数 n, 生成一个包含 1 到 n² 所有元素, 且元素按顺时针顺序螺旋排列的 n * n 正方形矩阵 matrix.

示例

输入: n = 3

输出: [[1, 2, 3], [8, 9, 4], [7, 6, 5]]

提示:

• 1 <= n <= 20

题解

跟 54. 螺旋矩阵 的思路差不多, 通过模拟, 按照螺旋矩阵的路线进行遍历, 并给 matrix 的指定位置赋值即可.

JavaScript

/**
 * @param {number} n
 * @return {number[][]}
 */
var generateMatrix = function (n) {
  const matrix = new Array(n).fill(0).map(() => new Array(n).fill(0))
  
  let top = 0,
    right = n - 1,
    bottom = n - 1,
    left = 0

  let val = 1

  while (val <= n * n) {
    for (let i = left; i <= right; i++, val++) matrix[top][i] = val
    top++

    for (let i = top; i <= bottom; i++, val++) matrix[i][right] = val
    right--

    for (let i = right; i >= left; i--, val++) matrix[bottom][i] = val
    bottom--

    for (let i = bottom; i >= top; i--, val++) matrix[i][left] = val
    left++
  }

  return matrix
}

Rust

pub fn generate_matrix(n: i32) -> Vec<Vec<i32>> {
    let n = n as usize;
    let mut matrix = vec![vec![0; n]; n];
    let (mut top, mut right, mut bottom, mut left) = (0, n - 1, n - 1, 0);
    let mut val = 1;

    while val <= (n * n) as i32 {
        for i in left..=right {
            matrix[top][i] = val;
            val += 1;
        }
        top += 1;

        for i in top..=bottom {
            matrix[i][right] = val;
            val += 1;
        }
        if right == 0 {
            break;
        }
        right -= 1;

        for i in (left..=right).rev() {
            matrix[bottom][i] = val;
            val += 1;
        }
        if bottom == 0 {
            break;
        }
        bottom -= 1;

        for i in (top..=bottom).rev() {
            matrix[i][left] = val;
            val += 1;
        }
        left += 1;
    }

    matrix
}