2.1.3搜索旋转排序数组

文章目录

• ​​1.题目要求​​
• ​​2.代码​​

1.题目要求

• ​​要求​​
• ​​思路​​

2.代码

class solution
{
    public:
            int search(vector<int>& nums, int target) 
            {
                int allnum = nums.size();
                if (allnum == 0)
                    return -1;
                if (allnum == 1)
                    return nums[allnum-1] == target ? 0 : -1;
                int low = 0;
                int high = allnum - 1;
                while (low <= high)
                {
                    int mid = (low + high)/2;
                    if (nums[mid] == target)
                        return mid;
                    
                    //判断分割出来的mid哪个部分有序，根据有序的那个部分确定我们该如何改变二分查找的上下界
                    if (nums[mid] >= nums[0])
                    {
                        if (nums[0] <= target && target <= nums[mid])
                            high = mid - 1;
                        else
                            low = mid + 1;
                        
                    }
                    else
                    {
                        if (nums[mid] < target && target <= nums[high])
                            low = mid + 1;
                        else
                            high = mid - 1;
                    }
                    
                }

                return -1;
            }
};