每日一道Leetcode -剑指 Offer 53 - I. 在排序数组中查找数字 I 【两次二分查找目标值所在的区间】

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        """
        找左右区间
        """
        i = 0
        j = len(nums)-1
        # 先找右边界吧
        while i<=j:
            mid = i + (j-i)//2
            if nums[mid] > target:
                j = mid-1
            elif nums[mid] <= target:
                i = mid + 1
        right = i
        # 如果数组中没有target，则提前结束
        if j >= 0 and nums[j]!=target:
            return 0
        # 查找完右边界后，左边界 left 一定在闭区间[0,j]之间
        i = 0
        while i <= j:
            mid = i + (j-i)//2
            if nums[mid] < target:
                i = mid + 1
            else:
                j = mid - 1
        left = j
        return right - left - 1