左闭右闭

left = 0;
right = numsize - 1;
while(left<=right)
{middle = (left+right)/2;if(nums[middle]>target){right = middle-1;}else if(nums[middle]<target){left = middle + 1;}else return middle;
}
return -1;

左闭右开

left = 0;right = numsize;
while(left<right)
{middle = (left+right)/2;if(nums[middle]>target){right = middle;}else if(nuns[middle]<target){left = middle+1;}else return middle;
}
return -1;