hdu 1025 dp 最长上升子序列

 1 //Accepted    4372 KB    140 ms
 2 //dp 最长上升子序列 nlogn
 3 #include <cstdio>
 4 #include <cstring>
 5 #include <iostream>
 6 using namespace std;
 7 const int imax_n = 500005;
 8 int dp[imax_n];
 9 int d[imax_n];
10 int a[imax_n];
11 int n;
12 int len;
13 int max(int a,int b)
14 {
15     return a>b?a:b;
16 }
17 int binary_search(int k)
18 {
19     int l=0;
20     int r=len;
21     while (l<=r)
22     {
23         int mid=(l+r)/2;
24         if (d[mid]==k) return mid;
25         if (d[mid]>k) r=mid-1;
26         if (d[mid]<k) l=mid+1;
27     }
28     return l;
29 }
30 void Dp()
31 {
32     memset(dp,0,sizeof(dp));
33     memset(d,0,sizeof(d));
34     len=-1;
35     for (int i=0;i<n;i++)
36     {
37         int j=binary_search(a[i]);
38         //printf("j=%d\n",j);
39         if (j>len) len++;
40         dp[i]=j+1;
41         d[j]=a[i];
42     }
43     int ans=0;
44     for (int i=0;i<n;i++)
45     ans=max(ans,dp[i]);
46     if (ans==1)
47     {
48         printf("My king, at most 1 road can be built.\n");
49     }
50     else
51     {
52         printf("My king, at most %d roads can be built.\n",ans);
53     }
54 }
55 int main()
56 {
57     int t=0;
58     while (scanf("%d",&n)!=EOF)
59     {
60         int x,y;
61         for (int i=0;i<n;i++)
62         {
63             scanf("%d%d",&x,&y);
64             a[x-1]=y;
65         }
66         printf("Case %d:\n",++t);
67         Dp();
68         printf("\n");
69     }
70     return 0;
71 }