日常被虐

列表嵌套展开

lst =[1,[2],[[3]],[[4,[5],6]],7,8,[9]]
def flat(nums):
    res = []
    for i in nums:
        if isinstance(i, list):
            res.extend(flat(i))
        else:
            res.append(i)
    return res

new_lst = flat(lst)
print(new_lst)

参考资料

字典互换键值对

三种方式交换键值对（前提：值唯一）：
1.
mydict={"a":1,"b":2,"c":3}
mydict_new={}
for key,val in mydict.items():
    mydict_new[val]=key

2.
mydict={"a":1,"b":2,"c":3}
mydict_new=dict([val,key] for key,val in mydict.items())

3.利用zip运算符：
mydict={"a":1,"b":2,"c":3}
mydict_new=dict(zip(mydict.values(),mydict.keys()))

参考资料
lambda

twosum

class Solution(object):
    def twoSum(self, nums, target):
        result = []
        for i in range(0,len(nums)):
            oneNum = nums[i]
            twoNum  = target - oneNum
            if twoNum in nums:
                j = nums.index(twoNum)
                if i != j:
                    result.append(i)
                    result.append(j)
                    return result

twosum