二分查找总结

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=100008;
int a[maxn];
int n;
int bs(int x)
{
int left=1,right=n;
while(left<=right)
{
int mid=(left+right)>>1;
if(a[mid]==x)
right=mid-1;
else	if(a[mid]>x)
right=mid-1;
else
left=mid+1;
}
return left+1;
}
int main()
{
int i,j,t,q,x,y;
scanf("%d",&t);
int cas=1;
while(t--)
{
scanf("%d%d",&n,&q);
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
sort(a+1,a+1+n);
printf("Case %d:\n",cas++);
while(q--)
{
scanf("%d%d",&x,&y);
int left=bs(x);
int right=bs(y+1);
printf("%d\n",right-left);
}
}
return 0;
}