Leetcode Exercise 3

Palindrome Number

Palindrome Number - LeetCode

Description

Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

判斷整數是否為迴文數，如果數字從後面讀過來和原來一樣就表示是迴文數

Example

#1
Input: 121
Output: true
#2
Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
#3
Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

構思

1. 先判斷是否小於0，若小於0，直接回傳false
2. 將數字轉成string
3. 和該string反轉做比較，並回傳結果

實作程式碼

# @param {Integer} x
# @return {Boolean}
def is_palindrome(x)
  if x < 0
    return false
  else
    x = x.to_s
    return x == x.reverse
  end     
end

to_s(base=10):

Returns a string containing the place-value representation of int with radix base(between 2 and 36).

to_s

reverse:

Returns a new string with the characters from str in reverse order.

reverse

結果

beats 100.00% 😀