class Solution:
def fib(self, n):
if n==0:
return 0
if n==1:
return 1
else:
return self.fib(n-1) + self.fib(n-2)
法一：暴力
class Solution:
def threeSumClosest(self, nums, target):
n = len(nums)
if n==3:
return sum(nums)
# 三数和与目标数差值
sumClosest = 10**4 + 10**3 + 1
threeSum = 0
for i in range(n):
for j in range(i+1,n):
for k in range(j+1,n):
threeS = nums[i] + nums[j] + nums[k]
if threeS == target:
return target
else:
temp = abs(target - threeS)
if temp < sumClosest:
threeSum = threeS
sumClosest = temp
return threeSum
法二：（受四数和启发）
class Solution:
def threeSumClosest(self, nums, target):
n = len(nums)
if n==3:
return sum(nums)
# 三数和与目标数差值
sumClosest = 10**4 + 10**3 + 1
towSum = dict()
for i in range(n):
for j in range(i+1,n):
if (nums[i] + nums[j]) not in towSum.keys():
towSum[nums[i] + nums[j]] = [[i,j]]
else:
towSum[nums[i] + nums[j]].append([i,j])
# 三数和
ps = 0
# 遍历原始数据列表
for k in range(n):
for t in towSum:
s = nums[k] + t
# 如果存在，且三个数坐在列表位置不同，直接返回target
if s == target:
for p in towSum[t]:
threeSet = set(p)
threeSet.add(k)
if len(threeSet) == 3:
return target
# 如果不存在
else:
# 找出三数与目标数最小差值，并返回三数
for p in towSum[t]:
threeSet = set(p)
threeSet.add(k)
if len(threeSet) == 3:
temp = abs(s - target)
if temp < sumClosest:
# print(temp)
sumClosest = temp
ps = s
return ps
Method 1:
Method 2:
# 法一
class Solution:
def search(self, nums, target):
for i,num in enumerate(nums):
if num == target:
return i
return -1
# 法二
class Solution:
def search(self, nums, target):
if target in nums:
return nums.index(target)
else:
return -1
Method 1:
Method 2:
class Solution:
def searchRange(self, nums, target):
n = len(nums)
if target not in nums:
return [-1,-1]
result = []
count = nums.index(target)
result.append(count)
if count+1 == n:
result.append(count)
for i in range(count+1,n):
if nums[i] == target:
if i == n-1:
result.append(i)
continue
else:
result.append(i-1)
break
return result
class Solution:
def isValidSudoku(self,board):
for i in range(3):
for j in range(3):
tempList = []
tempList += board[j*3][i*3:i*3+3]
tempList += board[j*3 + 1][i*3:i*3+3]
tempList += board[j*3 + 2][i*3:i*3+3]
tempList = [t for t in tempList if t!='.']
if len(tempList) != len(set(tempList)):
return False
for i in range(9):
tempList = [b for b in board[i] if b!='.']
if len(tempList) != len(set(tempList)):
return False
for j in range(9):
tempList = [b[j] for b in board if b[j]!='.']
if len(tempList) != len(set(tempList)):
return False
return True
class Solution:
def firstMissingPositive(self, nums):
nums = sorted(nums)
n = len(nums)
count = 0
# count_begin = 0
for i in range(n):
if nums[i] > 0:
count = i
break
nums = nums[count:]
# 去重后数组
numsList = []
# 去重操作
for num in nums:
if num not in numsList:
numsList.append(num)
n = len(numsList)
for i in range(n):
if numsList[i] != i+1:
return i+1
count = i+1
return count + 1
class Solution:
def multiply(self, num1, num2):
return str(int(num1)*int(num2))
class Solution:
def rotate(self, matrix):
"""
Do not return anything, modify matrix in-place instead.
"""
n = len(matrix)
d = []
for i in range(n):
d.append([m for m in matrix[i]])
for di in range(n):
for j in range(n):
matrix[j][n-1-di] = d[di][j]
return matrix
class Solution:
def groupAnagrams(self, strs):
d = dict()
n = len(strs)
countList = [0]*n
for s in strs:
if s not in d.keys():
d[s] = dict()
countList[strs.index(s)] = 1
for di in s:
if di not in d[s].keys():
d[s][di] = 1
else:
d[s][di] += 1
else:
countList[strs.index(s)] += 1
strsList = []
# 去重
for value in d.values():
if value not in strsList:
strsList.append(value)
resultList = []
count = 0
for val in strsList:
resultList.append([])
for dd in d:
if d[dd] == val:
for c in range(countList[strs.index(dd)]):
resultList[count].append(dd)
count += 1
return resultList
