""" First, see if target is larger then the largest or smaller then the smallest If it is out of range, it is not in the `nums`. Second, we use two pointers `l`, `r` to navigate our *binary search*. For every iteration, we choose the index, middle between `l` and `r` as `p`. If the value at `p` is larger than the target, we search the left-half by `r = p-1`. If the value at `p` is smaller than the target, we search the right-half by `l = p+1`. Continue this proccess, until we find the value. If we can't find the value, then `l` and `r` are going to collapse. `return -1` Another solution is to use [bisect](https://docs.python.org/2.7/library/bisect.html). """ class Solution(object): def search(self, nums, target): if nums is None or len(nums)==0: return -1 if target=l: if nums[l]==target: return l if nums[r]==target: return r p = (l+r)/2 if nums[p]==target: return p elif nums[p]>target: r = p-1 else: l = p+1 return -1 import bisect class Solution(object): def search(self, nums, target): if nums is None or len(nums)==0: return -1 if target