LC 數組二分

數組補題

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int len=nums.size();
        int temp=-1;
        int left=0,right=len-1;
        while(left<=right){
            int mid=(left+right)/2;
            if(target==nums[right]){ temp=right; break; }
            else if(target==nums[left]){ temp=left; break;}
            else if(target==nums[mid]){ temp=mid; break;}
            else if(target<nums[right]) {
                if(nums[mid]>nums[right] || target>nums[mid]) left=mid+1;
                else right=mid-1;
            }
            else if(target>nums[left]) {
                if(nums[mid]>nums[left] && target>nums[mid]) left=mid+1;
                else right=mid-1;
            }
            else break;
        }
        return temp;
    }
};