HDU-1025 Constructing Roads In JGShining's Kingdom O(nlogn)的最长上升子序列

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <queue>
#include <vector>
#include <cstdlib>
#include <algorithm>
using namespace std;
const int maxn=1021000;
struct node
{
int r;
int b;
int k;
}a[maxn];
int n;
int len;
int visit[maxn];
int dp[maxn];
bool cmp(node a,node b)
{
if(a.r==b.r)
{
return a.b>b.b;
}
return a.r<b.r;
}
int find(int i)
{
int low,high,mid;
low=1;
high=len;
while(low<=high)
{
int mid=(low+high)/2;
if(a[i].b==dp[mid])
{
return mid;
}
if(a[i].b<dp[mid])
{
high=mid-1;
}
else
{
low=mid+1;
}
}
return low;
}
int main()
{
int cas=1;
while(scanf("%d",&n)!=EOF)
{
memset(visit,0,sizeof(visit));
for(int i=1;i<=n;i++)
{
scanf("%d%d",&a[i].r,&a[i].b);
a[i].k=i;
}
sort(a+1,a+n+1,cmp);
dp[1]=a[1].b;
visit[1]=1;
len=1;
for(int i=2;i<=n;i++)
{
if(a[i].b>dp[len])
{
dp[++len]=a[i].b;
visit[i]=len;
}
else
{
int pos=find(i);
dp[pos]=a[i].b;
visit[i]=pos;
}
}
printf("Case %d:\n",cas++);
if(len==1)
{
printf("My king, at most %d road can be built.\n\n",len);
}

else
{
printf("My king, at most %d roads can be built.\n\n",len);
}
}
return 0;
}