树形DP UVA 1292 Strategic game

 

题目传送门

 1 /*
 2     题解：选择一个点，它相邻的点都当做被选择，问最少选择多少点将所有点都被选择
 3     树形DP：dp[i][0/1]表示当前点选或不选，如果选，相邻的点可选可不选，取最小值
 4 */
 5 /************************************************
 6  * Author        :Running_Time
 7  * Created Time  :2015-8-12 10:54:05
 8  * File Name     :UVA_1292.cpp
 9  ************************************************/
10 
11 #include <cstdio>
12 #include <algorithm>
13 #include <iostream>
14 #include <sstream>
15 #include <cstring>
16 #include <cmath>
17 #include <string>
18 #include <vector>
19 #include <queue>
20 #include <deque>
21 #include <stack>
22 #include <list>
23 #include <map>
24 #include <set>
25 #include <bitset>
26 #include <cstdlib>
27 #include <ctime>
28 using namespace std;
29 
30 #define lson l, mid, rt << 1
31 #define rson mid + 1, r, rt << 1 | 1
32 typedef long long ll;
33 const int MAXN = 1500 + 10;
34 const int INF = 0x3f3f3f3f;
35 const int MOD = 1e9 + 7;
36 vector<int> G[MAXN];
37 bool vis[MAXN];
38 int dp[MAXN][2];
39 int n;
40 
41 void DFS(int u) {
42     vis[u] = true;
43     for (int i=0; i<G[u].size (); ++i)  {
44         int v = G[u][i];
45         if (vis[v]) continue;
46         DFS (v);
47         dp[u][1] += min (dp[v][0], dp[v][1]);
48         dp[u][0] += dp[v][1];
49     }
50 }
51 
52 int main(void)    {     //UVA 1292 Strategic game
53     while (scanf ("%d", &n) == 1)   {
54         for (int i=0; i<n; ++i) G[i].clear ();
55         memset (dp, 0, sizeof (dp));
56         for (int i=0; i<n; ++i) dp[i][1] = 1;
57         memset (vis, false, sizeof (vis));
58 
59         for (int i=1; i<=n; ++i)    {
60             int u, v, num;   scanf ("%d:(%d)", &u, &num);
61             for (int j=1; j<=num; ++j)  {
62                 scanf ("%d", &v);
63                 G[u].push_back (v); G[v].push_back (u);
64             }
65         }
66 
67         DFS (1);
68         printf ("%d\n", min (dp[1][0], dp[1][1]));
69     }
70 
71     return 0;
72 }

 

posted @ 2015-08-12 14:41  Running_Time  阅读(179)  评论(0)  编辑  收藏  举报