目录
两数之和
我的答案
python
class Solution(object):
def twoSum(self, nums, target):
leng=len(nums)
for i in range(leng):
for j in range(leng):
if nums[i]+nums[j]==target and i!=j:
return [i,j]在b站up那里学到的【然后自己复写】
- 忘记怎么取list的第二个值了。【利用range的特性】
python
class Solution(object):
def twoSum(self, nums, target):
leng=len(nums)
for i in range(0,leng):
for j in range(i+1,leng):
if nums[i]+nums[j]==target and i!=j:
return [i,j]- 哈希表【空间换时间】
python
class Solution(object):
def twoSum(self, nums, target):
mapping = {}
for i in range(0, len(nums)):
mapping[nums[i]] = i
for j in range(0, len(nums)):
diff = target - nums[j]
if (diff in mapping and mapping[diff] != j):
return [j,mapping[diff]];和为 K 的子数组
在b站up那里学到的【然后自己复写】
python
class Solution(object):
def subarraySum(self, nums, k):
count = 0
dic={}
dic[0] = 1
cur_sum = 0
for num in nums:
cur_sum = cur_sum + num
if cur_sum-k in dic:# 很巧的思路
count=count+dic[cur_sum-k]
if cur_sum in dic:
dic[cur_sum] +=1
else:
dic[cur_sum] = 1
return count 三数之和
在b站up那里学到的【然后自己复写】
python
class Solution(object):
def threeSum(self, nums):
resol=[]
nums.sort()
for i in range(len(nums)):
cur = i
if nums[cur]>0:
return resol
if cur>0 and nums[cur-1] == nums[cur]:
continue # 去重
left = cur+1
right = len(nums)-1
while left<right:
total = nums[cur]+nums[left]+nums[right]
if total >0:
right-=1
elif total<0:
left+=1
else:
resol.append([nums[cur],nums[left],nums[right]])
while left<right and nums[right-1]==nums[right]:# 去重
right-=1
while left<right and nums[left+1]==nums[left]:# 去重
left+=1
right-=1
left+=1
return resol两数相加【链表】
我的半路答案：没有看到是链表
- 我还没有写完，只是想半路测一下是否正确。
- 关于链表的话，我相对还是弱一点，下次巩固。
python
class Solution(object):
def addTwoNumbers(self, l1, l2):
resl=[]
cur=0
len1=len(l1)
len2=len(l2)
for i in range(min(len1,len2)):
total=l1[i]+l2[i]+cur
if total>10:
cur=total/10
resl.append(total%10)
else:
resl.append(total)
return resl在b站up那里学到的【复写失败后整理】
python
class Solution(object):
def addTwoNumbers(self, l1, l2):
total = 0
next1 = 0
dummy = ListNode()
cur = dummy#############必须得要一个临时变量，因为后面输出是从头开始输出
while (l1 != None and l2 != None):
total = l1.val + l2.val + next1
cur.next = ListNode(total % 10)
next1 = total // 10
cur = cur.next##################不要忘记
l1 = l1.next
l2 = l2.next
while l1 != None:
total = l1.val + next1
cur.next = ListNode(total % 10)
next1 = total // 10
cur = cur.next##################不要忘记
l1 = l1.next
while l2 != None:
total = l2.val + next1
cur.next = ListNode(total % 10)
next1 = total // 10
cur = cur.next##################不要忘记
l2 = l2.next
if next1 != 0:
cur.next = ListNode(next1)
return dummy.next