Leetcode刷题-编程基础

2235

class Solution:
    def sum(self, num1: int, num2: int) -> int:
        return num1 + num2

2469

class Solution:
    def convertTemperature(self, celsius: float) -> List[float]:
        return [celsius+273.15,celsius*1.80 + 32.00]

2413

class Solution:
    def smallestEvenMultiple(self, n: int) -> int:
        if n%2 == 0:
            return n
        else:
            return 2*n

2236

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def checkTree(self, root: Optional[TreeNode]) -> bool:
        left = root.left.val
        right = root.right.val
        if left + right == root.val:
            return True
        else:
            return False

1486

class Solution:
    def xorOperation(self, n: int, start: int) -> int:
        res = start
        for i in range(1,n):
            res = res ^ (start + i*2)
        return res

1512

class Solution:
    def numIdenticalPairs(self, nums: List[int]) -> int:
        res = 0
        for i , x in enumerate(nums):
            for j , y in enumerate(nums):
                if i < j and x == y:
                    res += 1
        return res

1534

class Solution:
    def countGoodTriplets(self, arr: List[int], a: int, b: int, c: int) -> int:
        n = len(arr)
        res = 0
        for i in range(n):
            for j in range(n):
                for k in range(n):
                    if not i < j < k:
                        continue
                    if abs(arr[i] - arr[j]) <= a and abs(arr[j] - arr[k]) <= b and abs(arr[i] - arr[k]) <= c:
                        res += 1
        return res

584

# Write your MySQL query statement below
SELECT name FROM customer WHERE referee_id <> 2 OR referee_id IS NULL;

在MySQL中，需要对NULL进行特殊判断，上题中如果只判断是否等于2，会忽略掉id为NULL的行。（MySQL 使用三值逻辑 —— TRUE, FALSE 和 UNKNOWN）当我们拿一个非NULL值和一个NULL值，或者两个NULL值来比较时，会返回UNKNOWN。

1757

# Write your MySQL query statement below
Select product_id
from Products
where low_fats = 'Y' and recyclable = 'Y';

709

class Solution:
    def toLowerCase(self, s: str) -> str:
        return s.lower()
        

258

class Solution:
    def addDigits(self, num: int) -> int:
        if num == 0:
            return num
        return (num - 1)%9 + 1
        

1281

class Solution:
    def subtractProductAndSum(self, n: int) -> int:
        flag = 1
        num = int(n)
        s = 0
        a = 1
        while num > 0:
            s += int(num%10)
            a *= int(num%10)
            if num%10 == 0:
                flag = 0
            num //= 10
        return a - s
        
        

231

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        if n == 1:
            return True
        if n%2 == 1 or n == 0:
            return False
        while math.fabs(n) > 0:
            if n%2 == 1 and n != 1:
                return False
            n /= 2
        return True
        

326

class Solution:
    def isPowerOfThree(self, n: int) -> bool:
        m = 1
        while m < n:
            m *= 3
        if m == n:
            return True
        else:
            return False
        
        

263

class Solution:
    def isUgly(self, n: int) -> bool:
        if n <= 0:
            return False
        while n > 1:
            if n % 2 == 0:
                n //= 2
            elif n % 3 == 0:
                n //= 3
            elif n % 5 == 0:
                n //= 5
            else:
                return False
        return True        

1470

class Solution:
    def shuffle(self, nums: List[int], n: int) -> List[int]:
        res = []
        i = 0
        j = n
        while i < n and j < 2*n:
            res.append(nums[i])
            res.append(nums[j])
            i += 1
            j += 1
        return res

867

class Solution:
    def transpose(self, matrix: List[List[int]]) -> List[List[int]]:
        res = [[0 for _ in range(len(matrix))] for _ in range(len(matrix[0]))]
        for i in range(len(matrix)):
            for j in range(len(matrix[0])):
                res[j][i] = matrix[i][j]
        return res
        

1422

class Solution:
    def maxScore(self, s: str) -> int:
        mid = 1
        l = len(s)
        res = 0
        while mid < l:
            ans = 0
            for i in range(mid):
                if s[i] == '0':
                    ans += 1
            for j in range(mid,l):
                if s[j] == '1':
                    ans += 1
            mid += 1
            res = max(res,ans)
        return res
        

2586

class Solution:
    def vowelStrings(self, words: List[str], left: int, right: int) -> int:
        res = 0
        for i in range(left,right + 1):
            if words[i].startswith('a') or words[i].startswith('e') or words[i].startswith('i') or words[i].startswith('o') or words[i].startswith('u'):
                if words[i].endswith('a') or words[i].endswith('e') or words[i].endswith('i') or words[i].endswith('o') or words[i].endswith('u'):
                    res += 1
        return res
        

852

class Solution:
    def peakIndexInMountainArray(self, arr: List[int]) -> int:
        left = 0
        right = len(arr) - 2
        while left + 1 < right:
            mid = (left + right) // 2
            if arr[mid + 1] < arr[mid]:
                right = mid
            else:
                left = mid
        return right