2021-11-16thought

class Solution:
    def maxSubArray(self, nums: List[int]) -> int:
        if len(nums) == 1:
            return nums[0]
        curr = nums[0]
        max_sum = nums[0]
        for i in range (1,len(nums)):
            if curr<0:
                curr = nums[i]
            else:
                curr += nums[i]
            max_sum = max(max_sum,curr)
        return max_sum

动态规划

class Solution:
    def maxSubArray(self, nums: List[int]) -> int:
        dp = [0]*len(nums)
        dp[0] = nums[0]
        result = nums[0]
        for i in range(1,len(nums)):
            dp[i] = max(dp[i-1]+nums[i],nums[i])
            result = max(result,dp[i])
        return result

滑动窗口

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        n = len(s)
        left,right = 0,0
        window = []
        max_len = 0
        if n<=1:
            return n
        while right<n:
            if s[right] not in window:
                max_len = max(max_len,right-left+1)
                window.append(s[right])
                right += 1
            else:
                window.remove(s[left])
                left += 1
        return max_len

暴力法：

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        result = []
        for i in range(0,len(nums)):
            for j in range(i+1,len(nums)):
                sum = nums[i]+nums[j]
                if sum == target:
                    result.append(i)
                    result.append(j)
                    return result

哈希表

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        result = []
        map = {}
        for i in range(0,len(nums)):
            map[nums[i]] = i
        for j in range(0,len(nums)):
            num = target-nums[j]
            if num in map and map[num]!=j:
                result.append(j)
                result.append(map[num])
                return result

最小堆

class Solution:
    def findKthLargest(self, nums: List[int], k: int) -> int:
        minheap = []
        heapify(minheap)
        for num in nums:
            heappush(minheap,num)
            if len(minheap)>k:
                heappop(minheap)
        return minheap[0]

先排序后找

class Solution:
    def findKthLargest(self, nums: List[int], k: int) -> int:
        nums.sort()
        n = len(nums)
        return  nums[n-k]

纯属记录：部分代码参考B站博主