class Solution(object):
def findMedianSortedArrays(self, nums1, nums2):
# 将一个集合划分为两个长度相等的子集，其中一个子集中的元素总是大于另一个子集中的元素
m, n = len(nums1), len(nums2)
if m>n: nums1,nums2,m,n = nums2,nums1,n,m
imin, imax, half_len = 0, m, (m+n+1)/2
while imin<=imax:
i = (imin+imax)/2
j = half_len-i
if i<m and nums2[j-1]>nums1[i]:
imin += 1
elif i>0 and nums1[i-1]>nums2[j]:
imax -= 1
else:
if i==0: max_left = nums2[j-1]
elif j==0: max_left = nums1[i-1]
else: max_left = max(nums1[i-1], nums2[j-1])
if (m+n)%2: return max_left
if i==m: min_right = nums2[j]
elif j==n: min_right = nums1[i]
else: min_right = min(nums1[i], nums2[j])
return (max_left+min_right)/2.0
# 求解
s=Solution()
s.findMedianSortedArrays([1,3], [2])
# return
2.0
leetcode 9.回文数
class Solution(object):
def isPalindrome(self, x):
# 作弊法
return str(x)==str(x)[::-1]
def isPalindrome(self, x):
# 指针
if x<0: return False
x = str(x)
n = len(x)
left, right = 0, n-1
while left<=right:
if x[left]==x[right]:
left += 1
right -= 1
else:
return False
return True
class Solution(object):
def maxArea(self, height):
n = len(height)
i, j, maxarea = 0, n-1, 0
while i>=0 and j<n and i<j:
left = height[i]
right = height[j]
h = min(left, right)
w = j-i
maxarea = max(maxarea, h*w)
if h==left:
i += 1
else:
j -= 1
return maxarea
# 求解
s = Solution()
s.maxArea([1,8,6,2,5,4,8,3,7])
# return
49
class Solution(object):
def search(self, nums, target):
if not nums: return -1
n = len(nums)
left, right = 0, n-1
while left<right:
mid = left + (right-left)//2
if nums[mid]==target:
return mid
elif nums[left]<=nums[mid]:
if nums[left]<=target<nums[mid]:
right = mid-1
else:
left = mid+1
else:
if nums[mid]<target<=nums[right]:
left = mid+1
else:
right = mid-1
return left if nums[left]==target else -1
class Solution(object):
def searchRange(self, nums, target):
if not nums: return [-1, -1]
n = len(nums)
left, right = 0, n-1
if left==right and nums[left]==target: return [left, right]
while left<right:
if nums[left]<target: left += 1
if nums[right]>target: right -= 1
if nums[left]==nums[right]==target: return [left, right]
return [-1, -1]
class Solution(object):
def searchInsert(self, nums, target):
n = len(nums)
left, right =0, n-1
if nums[left]>target: return left
if nums[right]<target: return right+1
while left<right:
mid = left + (right-left)//2
if nums[mid] == target:
return mid
elif nums[mid]<target:
left = mid+1
else:
right = mid
return left
leetcode 42.接雨水
class Solution(object):
def trap(self, height):
if not height: return 0
n = len(height)
left, right, sum = 0, n-1, 0
max_left = height[left]
max_right = height[right]
while left<right:
max_left = max(height[left], max_left)
max_right = max(height[right], max_right)
if max_left<max_right:
sum += max_left-height[left]
left += 1
else:
sum += max_right-height[right]
right -= 1
return sum
class Solution(object):
def searchMatrix(self, matrix, target):
# 剔除特殊情况
if not matrix or not matrix[0]: return False
if target<matrix[0][0] or target>matrix[-1][-1]: return False
# 定位到行
row, col, i = len(matrix), len(matrix[0]), 0
while i<row and target>matrix[i][-1]: i += 1
# 二分查找
left, right = 0, col-1
while left<right:
mid = left + (right-left)//2
if matrix[i][mid]==target:
return True
elif matrix[i][mid]<target:
left = mid+1
else:
right = mid
return True if matrix[i][left]==target else False
class Solution(object):
def search(self, nums, target):
if not nums: return False
n = len(nums)
left, right = 0, n-1
while left<=right:
mid = left + (right-left)//2
if nums[mid]==target:
return True
if nums[mid]==nums[left]==nums[right]:
left += 1
right -= 1
elif nums[left]<=nums[mid]:
if nums[left]<=target<nums[mid]:
right = mid - 1
else:
left = mid + 1
else:
if nums[mid]<target<=nums[right]:
left = mid + 1
else:
right = mid -1
return False
leetcode 125.验证回文串
class Solution(object):
def isPalindrome(self, s):
# 双指针
n = len(s)
left, right = 0, n-1
while left<right:
while left<right and not s[left].isalnum():
left += 1
while left<right and not s[right].isalnum():
right -= 1
if s[left].lower() != s[right].lower():
return False
left += 1
right -= 1
return True
class Solution(object):
def findMin(self, nums):
n = len(nums)
left, right = 0, n-1
while left<right:
mid = left + (right-left)//2
if nums[mid]>nums[right]:
left = mid+1
else:
right = mid
return nums[left]
class Solution(object):
def findMin(self, nums):
if not nums: return
n = len(nums)
left, right = 0, n-1
while left<right:
while left<right and nums[left]==nums[left+1]: left += 1
while left<right and nums[right]==nums[right-1]: right -= 1
mid = left + (right-left)//2
if nums[mid]>nums[right]:
left = mid + 1
else:
right = mid
return nums[left]
leetcode 162.寻找峰值
class Solution(object):
def findPeakElement(self, nums):
if not nums: return
n = len(nums)
left, right = 0, n-1
while left<right:
mid = left + (right-left)//2
if nums[mid]<nums[mid+1]:
left = mid+1
else:
right = mid
return left
class Solution(object):
def twoSum(self, numbers, target):
if not numbers: return []
n = len(numbers)
left, right = 0, n-1
while left<right:
total = numbers[left]+numbers[right]
if total<target:
left += 1
elif total>target:
right -= 1
else:
return [left+1, right+1]
return []
