插入位置

class Solution{
public:
    int searchInsert(std::vector<int> &nums, int target){
        int index = -1;//最终返回的下标，否则为需要插入的位置；
        int begin = 0;
        int end = noms.size() -1;
        while( index == -1){//若index == -1，则说明还未找到正确位置，持续二分搜索
            int mid == (begin + end) / 2;
            if(target ==nums[mid]){
                index = mid;
            }
            else if(target < nums[mid]){
                if(mid == 0 || target > nums[mid-1]){
                    index = mid;
                    }  
                 end = mid -1; 
             }
             else if(target > nums[mid] || mid == nums.size()-1){
                  if(target < nums[mid+1]){
                      return index = mid+1;
                  }
                  begin = mid +1 ;
              }
            
        }
        return index;
    }
};