資工趴趴熊的小天地

C++

/*
Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4
*/ 

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int left=0;
        int right=nums.size()-1;
        
        while(left<=right){
        	int middle=left+((right-left)/2);//防止溢出
			if(nums[middle]>target){
				right=middle-1;
			} 
			else if(nums[middle]<target){
				left=middle+1;
			}
			else return middle; //找到 
		}
		return -1; //未找到 
    }
};

python:

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        left, right = 0, len(nums) - 1
        
        while left <= right:
            middle = (left + right) // 2

            if nums[middle] < target:
                left = middle + 1
            elif nums[middle] > target:
                right = middle - 1
            else:
                return middle
        return -1