Javascript in Leetcode 13–15|面試問題
![](https://assets.matters.news/embed/9849dcd5-537c-4cc7-bbbf-b2dd26493fb4.jpeg)
目錄
- 13-Roman-to-Integer
- 14-Longest-Common-Prefix
- 15–3Sum
找到source code | Github
13. Roman to Integer
Roman numerals are represented by seven different symbols: I
, V
, X
, L
, C
, D
and M
.
Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000
For example, 2
is written as II
in Roman numeral, just two ones added together. 12
is written as XII
, which is simply X + II
. The number 27
is written as XXVII
, which is XX + V + II
.
Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII
. Instead, the number four is written as IV
. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX
. There are six instances where subtraction is used:
I
can be placed beforeV
(5) andX
(10) to make 4 and 9.X
can be placed beforeL
(50) andC
(100) to make 40 and 90.C
can be placed beforeD
(500) andM
(1000) to make 400 and 900.
Given a roman numeral, convert it to an integer.
Example 1:
Input: s = "III" Output: 3 Explanation: III = 3.
Example 2:
Input: s = "LVIII" Output: 58 Explanation: L = 50, V= 5, III = 3.
Example 3:
Input: s = "MCMXCIV" Output: 1994 Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
Constraints:
1 <= s.length <= 15
s
contains only the characters('I', 'V', 'X', 'L', 'C', 'D', 'M')
.- It is guaranteed that
s
is a valid roman numeral in the range[1, 3999]
.
![](https://assets.matters.news/embed/cdf3a663-e530-4aca-aeb4-54da89812ce0.png)
14. Longest Common Prefix
Write a function to find the longest common prefix string amongst an array of strings.
If there is no common prefix, return an empty string ""
.
Example 1:
Input: strs = ["flower","flow","flight"] Output: "fl"
Example 2:
Input: strs = ["dog","racecar","car"] Output: "" Explanation: There is no common prefix among the input strings.
Constraints:
1 <= strs.length <= 200
0 <= strs[i].length <= 200
strs[i]
consists of only lowercase English letters.
![](https://assets.matters.news/embed/499275df-d7db-4919-9b78-a3e6bbb5c0fe.png)
15. 3Sum
Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]]
such that i != j
, i != k
, and j != k
, and nums[i] + nums[j] + nums[k] == 0
.
Notice that the solution set must not contain duplicate triplets.
Example 1:
Input: nums = [-1,0,1,2,-1,-4] Output: [[-1,-1,2],[-1,0,1]]
Example 2:
Input: nums = [] Output: []
Example 3:
Input: nums = [0] Output: []
![](https://assets.matters.news/embed/e4bf6f80-5e47-4468-89f7-cc7b69d77c37.png)
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