LeetCode-54. Spiral Matrix

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问题描述

Given an m x n matrix, return all elements of the matrix in spiral order.

Example :

img

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

Constraints:

  • m == matrix.length
  • n == matrix[i].length
  • 1 <= m, n <= 10
  • -100 <= matrix[i][j] <= 100

解答

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/*
 * @Description: 54. Spiral Matrix
 * @Author: libk
 * @Github: https://github.com/libk
 */
/**
 * @param {number[][]} matrix
 * @return {number[]}
 */
const spiralOrder = function (matrix) {
  if (!matrix || !matrix.length || !matrix[0].length) {
    return []
  }

  const rowLen = matrix.length - 1
  const colLen = matrix[0].length - 1
  let top = 0
  let left = 0
  let bottom = rowLen
  let right = colLen

  const path = []

  while (top <= bottom && left <= right) {
    for (let col = left; col <= right; col++) {
      path.push(matrix[top][col])
    }
    for (let row = top + 1; row <= bottom; row++) {
      path.push(matrix[row][right])
    }
    // top===bottom或left===right时，说明只剩最后一行或者一列      
    if (top < bottom && left < right) {
      for (let col = right - 1; col >= left; col--) {
        path.push(matrix[bottom][col])
      }
      for (let row = bottom - 1; row > top; row--) {
        path.push(matrix[row][left])
      }
    }
    top++
    left++
    bottom--
    right--
  }
  return path
}