hdu1025

#include<stdio.h>
const int MAXN=500010;
int a[MAXN],b[MAXN];

//用二分查找的方法找到一个位置，使得num>b[i-1] 并且num<b[i],并用num代替b[i]
int Search(int num,int low,int high)
{
int mid;
while(low<=high)
{
mid=(low+high)/2;
if(num>=b[mid]) low=mid+1;
else high=mid-1;
}
return low;
}
int DP(int n)
{
int i,len,pos;
b[1]=a[1];
len=1;
for(i=2;i<=n;i++)
{
if(a[i]>=b[len])//如果a[i]比b[]数组中最大还大直接插入到后面即可
{
len=len+1;
b[len]=a[i];
}
else//用二分的方法在b[]数组中找出第一个比a[i]大的位置并且让a[i]替代这个位置
{
pos=Search(a[i],1,len);
b[pos]=a[i];
}
}
return len;
}
int main()
{

int n;
int iCase=0;
int i,j;
int x,y;
while(scanf("%d",&n)!=EOF)
{
iCase++;
for(i=1;i<=n;i++)
{
scanf("%d%d",&x,&y);
a[x]=y;
}
int res=DP(n);
printf("Case %d: ",iCase);
if(res==1)
{
printf("My king, at most 1 road can be built. ");
}
else
printf("My king, at most %d roads can be built. ",res);
}
return 0;
}