代码

bool first = 1;
int lst, lstx;

int l, r;
int binary_search(const unsigned *a, int n, unsigned x)
{
if (first)
{
first = 0;
l=0;r=n-1;
}
else
{
if(x==lstx)return lst;
if(x>lstx)l=lst+1,r=n-1;
else l=0,r=lst-1;
}
lstx=x;
while(l<=r){
int mid=l+r>>1;
if(a[mid]==x)return lst=mid;
else if(a[mid]>x)l=mid+1;
else r=mid-1;
}
return lst;
}

评测结果