leetcode-1905-山脉数组中查找目标值

 

方法：二分查找

def binary_search(mountain, target, l, r, key=lambda x: x):
    target = key(target)
    while l <= r:
        mid = (l + r) // 2
        cur = key(mountain.get(mid))
        if cur == target:
            return mid
        elif cur < target:
            l = mid + 1
        else:
            r = mid - 1
    return -1

class Solution:
    def findInMountainArray(self, target: int, mountain_arr: 'MountainArray') -> int:
        l, r = 0, mountain_arr.length() - 1
        while l < r:
            mid = (l + r) // 2
            if mountain_arr.get(mid) < mountain_arr.get(mid + 1):
                l = mid + 1
            else:
                r = mid
        peak = l
        index = binary_search(mountain_arr, target, 0, peak)
        if index != -1:
            return index
        index = binary_search(mountain_arr, target, peak + 1, mountain_arr.length() - 1, lambda x: -x)
        return index

 

 

 

def binary_search(mountain, target, l, r, key=lambda x: x):

    target = key(target)

    while l <= r:

        mid = (l + r) // 2

        cur = key(mountain.get(mid))

        if cur == target:

            return mid

        elif cur < target:

            l = mid + 1

        else:

            r = mid - 1

    return -1

class Solution:

    def findInMountainArray(self, target: int, mountain_arr: 'MountainArray') -> int:

        l, r = 0, mountain_arr.length() - 1

        while l < r:

            mid = (l + r) // 2

            if mountain_arr.get(mid) < mountain_arr.get(mid + 1):

                l = mid + 1

            else:

                r = mid

        peak = l

        index = binary_search(mountain_arr, target, 0, peak)

        if index != -1:

            return index

        index = binary_search(mountain_arr, target, peak + 1, mountain_arr.length() - 1, lambda x: -x)

        return index