Search for a Range

Problem

Given a sorted array of integers, find the starting and ending position of a given target value.

Your algorithm's runtime complexity must be in the order of O(log n).

If the target is not found in the array, return [-1, -1].

For example,
Given [5, 7, 7, 8, 8, 10] and target value 8,
return [3, 4].

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Idea

search lower bound from left->right; then search upper bound from right->left

当ector里没有元素时不能通过数组来赋值

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Solution

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