HDU-1176 免费馅饼 ( DP )

 1 #include<iostream>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 
 6 int t, n;
 7 int pi[100005][12];
 8 int fall[100005][12];
 9 int ans;
10 
11 int main(){
12     ios::sync_with_stdio( false );
13 
14     while( cin >> n, n ){
15         memset( pi, 0, sizeof( pi ) );
16         memset( fall, 0, sizeof( fall ) );
17         ans = 0;
18         t = 0;
19 
20         int a, b;
21         for( int i = 0; i < n; i++ ){
22             cin >> a >> b;
23             fall[b][a]++;
24             t = max( t, b );
25         }
26 
27         pi[1][4] = fall[1][4];
28         pi[1][5] = fall[1][5];
29         pi[1][6] = fall[1][6];
30         for( int i = 2; i <= t; i ++){
31             for( int j = 0; j <= 10; j++ ){
32                 if( !( i + j >= 5 && i - j >= -5 ) ) continue;//这句不要也能A，个人感觉数据不严谨
33                 pi[i][j] = pi[i - 1][j];
34                 if( j > 0 ) pi[i][j] = max( pi[i][j], pi[i - 1][j-1] );
35                 if( j <10 ) pi[i][j] = max( pi[i][j], pi[i - 1][j + 1] );
36                 pi[i][j] += fall[i][j];
37             }
38         }
39 
40         for( int i = 0; i <= 10; i++ )
41             ans = max( ans, pi[t][i] );
42 
43         cout << ans << endl;
44     }
45 
46     return 0;
47 }