第 375 场周赛(滑动窗口，区间合并)-526互联

使用差分的思想进行解决

class Solution:
    def countTestedDevices(self, batteryPercentages: List[int]) -> int:
        diff = 0
        for x in batteryPercentages:
            if x > diff:
                diff += 1
        return diff

class Solution:
    def getGoodIndices(self, variables: List[List[int]], target: int) -> List[int]:
        return [i for i, (a, b, c, m) in enumerate(variables)
                if pow(pow(a, b, 10), c, m) == target]

这两题比较简单，我也是赛后看了灵神的代码，实在是太优雅了，贴在这里以后看一看。

第三题仍然是滑动窗口，也是在这次周赛和双周赛后从灵神题解中学到的写法，极其优雅。

class Solution:
    def countSubarrays(self, nums: List[int], k: int) -> int:
        n = len(nums)
        mx = max(nums)
        cnt = 0
        res = left = 0
        for v in nums:
            if v == mx:
                cnt += 1
            while cnt >= k:
                if nums[left] == mx:
                    cnt -= 1
                left += 1
            res += left
        
        return res

class Solution:
    def numberOfGoodPartitions(self, nums: List[int]) -> int:
        r = {}
        for i, x in enumerate(nums):
            r[x] = i
        
        m = max_r = 0
        for i, x in enumerate(nums):
            max_r = max(max_r, r[x])
            if max_r == i:
                m += 1
        
        return pow(2, m - 1, 10**9 + 7)