59. 螺旋矩阵 II

[wengzc]

给定一个正整数 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正方形矩阵。

示例:

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

题目链接：https://leetcode-cn.com/problems/spiral-matrix-ii

[wengzc]

解法一

• 相似题目：54. 螺旋矩阵

/**
 * @param {number} n
 * @return {number[][]}
 */
var generateMatrix = function (n) {
    let arr = new Array(n)
    for (let i = 0; i < n; i++) {
        arr[i] = new Array(n)
    }
    let u = 0, d = n - 1, l = 0, r = n - 1
    let count = 1
    while (true) {
        for (let i = l; i <= r; i++) arr[u][i] = count++
        if (++u > d) break
        for (let i = u; i <= d; i++) arr[i][r] = count++
        if (--r < l) break
        for (let i = r; i >= l; i--) arr[d][i] = count++
        if (--d < u) break
        for (let i = d; i >= u; i--) arr[i][l] = count++
        if (++l > r) break
    }
    return arr
};

解法二

/**
 * @param {number} n
 * @return {number[][]}
 */
var generateMatrix = function (n) {
  let arr = new Array(n)
  for (let i = 0; i < n; i++) {
    arr[i] = new Array(n)
  }
  let u = 0, d = n - 1, l = 0, r = n - 1
  let count = 1
  let limit = n * n
  while (count <= limit) {
    for (let i = l; i <= r; i++) arr[u][i] = count++
    ++u
    for (let i = u; i <= d; i++) arr[i][r] = count++
    --r
    for (let i = r; i >= l; i--) arr[d][i] = count++
    --d
    for (let i = d; i >= u; i--) arr[i][l] = count++
    ++l
  }
  return arr
};