前言
本系列博客为平时刷LeetCode的记录，每十道题一篇博客，持续更新，所有代码详见GitHub：https://github.com/roguesir/LeetCode-Algorithm
1. Two Sum
Introduction
Given an array of integers, return indices of the two numbers such that they add up to a specific target.
You may assume that each input would have exactly one solution, and you may not use the same element twice.
Example:
Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].
Solution
class Solution(object):
def twoSum(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: List[int]
"""
res = {}
for i in range(len(nums)):
reduce_ = target - nums[i]
if res.get(reduce_) is not None:
return [i, res[reduce_]]
res[nums[i]] = i
7. Reverse Integer
Introduction
Given a 32-bit signed integer, reverse digits of an integer.
Example 1:
Input: 123
Output: 321
Example 2:
Input: -123
Output: -321
Example 3:
Input: 120
Output: 21
Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
Solution
class Solution(object):
def reverse(self, x):
"""
:type x: int
:rtype: int
"""
x = str(x)
y = ""
if x[0] == "-":
y = y + x[0]
for i in range(len(x)-1, 0, -1):
y += x[i]
else:
for i in range(len(x)-1, -1, -1):
y += x[i]
if int(y) > 2**31-1 or int(y) < -2**31:
return 0
else:
return int(y)
9. Palindrome Number
Introduction
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
Example 1:
Input: 121
Output: true
Example 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.
Example 3:
Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
Follow up:
Coud you solve it without converting the integer to a string?
Solution
class Solution(object):
def isPalindrome(self, x):
"""
:type x: int
:rtype: bool
"""
x = str(x)
out = True
for i in range(len(x)/2):
if x[i] == x[len(x)-1-i]:
continue
else:
out = False
break
return out
https://leetcode.com/submissions/detail/202027004/
- 更新时间：2019-01-27