题解 | #二分查找-II#

    int search(vector<int>& nums, int target) {
        int index=nums.size();
        int left=0,right=nums.size()-1;
        while(left<=right)
        {
            int mid=(left+right)/2;
            if(nums[mid]<target)
                left=mid+1;
            else
            {
                if(nums[mid]==target)
                    index=min(index,mid);
                right=mid-1;
            }
        }
        if(index==nums.size())
            return -1;
        return index;
    }
};

使用二分法查找，index始终是相等的数中索引最小的