LeetCode Js-58. Length of Last Word

    AllenLi
    LeetCode Js-String

    Given a string s consisting of words and spaces, return the length of the last word in the string.
    A word is a maximal substring consisting of non-space characters only.

    給予一個有文字與空格的s字串，回傳最後字串的文字長度。
單字是由非空格組成之字串。

    Example 1:

    Input: s = "Hello World"
Output: 5
Explanation: The last word is "World" with length 5.

    Example 2:

    Input: s = "   fly me   to   the moon  "
Output: 4
Explanation: The last word is "moon" with length 4.

    Example 3:

    Input: s = "luffy is still joyboy"
Output: 6
Explanation: The last word is "joyboy" with length 6.

    Solution:
    1. 運用.trim()移除字串中，字首前、字尾後的空白。
    2. 使用.split(‘ ‘)來將字串以空白做切割為陣列。
    3. 注意陣列與數列的關係。
    ex.
    word = [a, b, c]
    array 0 1 2

    Code:

    var lengthOfLastWord = function(s) {
    const arr = s.trim().split(' ')
    return arr[arr.length - 1].length
};

    FlowChart:
    Example 1

    step.1
string    1        2
arr = ['Hello', 'World']
array     0        1
arr.length = 2
return arr[arr.length - 1].length 
//arr[1].length => 'World'.length => 5

    Example 2

    step.2
string   1      2    3   4    5    6   7    8       9
arr = ['fly', 'me', '', '', 'to', '', '', 'the', 'moon']
array    0      1    2   3    4    5   6    7       8
arr.length = 9
return arr[arr.length - 1].length 
//arr[8].length => 'moon'.length => 4

    Example 3

    step.3
string    1       2      3         4  
arr = ['luffy', 'is', 'still', 'joyboy']
array     0       1      2         3  
arr.length = 4
return arr[arr.length - 1].length 
//arr[3].length => 'joyboy'.length =>6

    Code 2:

    var lengthOfLastWord = function(s) {
  if (s.length === 0) return 0
  let arr = s.trim().split(' ')

  for (let i = arr.length - 1; i >= 0; i--) {
    if (arr[i].length > 0) {
      return arr[i].length
    }
  }
};

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