POJ 1947 Rebuilding Roads

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cstdio>
 4 #include<cstring>
 5 #include<cmath>
 6 #include<cstdlib>
 7 #include<vector>
 8 using namespace std;
 9 typedef long long ll;
10 typedef long double ld;
11 typedef pair<int,int> pr;
12 const double pi=acos(-1);
13 #define rep(i,a,n) for(int i=a;i<=n;i++)
14 #define per(i,n,a) for(int i=n;i>=a;i--)
15 #define Rep(i,u) for(int i=head[u];i;i=Next[i])
16 #define clr(a) memset(a,0,sizeof(a))
17 #define pb push_back
18 #define mp make_pair
19 #define fi first
20 #define sc second
21 #define pq priority_queue
22 #define pqb priority_queue <int, vector<int>, less<int> >
23 #define pqs priority_queue <int, vector<int>, greater<int> >
24 #define vec vector
25 ld eps=1e-9;
26 ll pp=1000000007;
27 ll mo(ll a,ll pp){if(a>=0 && a<pp)return a;a%=pp;if(a<0)a+=pp;return a;}
28 ll powmod(ll a,ll b,ll pp){ll ans=1;for(;b;b>>=1,a=mo(a*a,pp))if(b&1)ans=mo(ans*a,pp);return ans;}
29 void fre() { freopen("c://test//input.in", "r", stdin); freopen("c://test//output.out", "w", stdout); }
30 //void add(int x,int y,int z){ v[++e]=y; next[e]=head[x]; head[x]=e; cost[e]=z; }
31 int dx[5]={0,-1,1,0,0},dy[5]={0,0,0,-1,1};
32 ll read(){ ll ans=0; char last=‘ ‘,ch=getchar();
33 while(ch<‘0‘ || ch>‘9‘)last=ch,ch=getchar();
34 while(ch>=‘0‘ && ch<=‘9‘)ans=ans*10+ch-‘0‘,ch=getchar();
35 if(last==‘-‘)ans=-ans; return ans;
36 }
37 const int M=1000,N=200,inf=1e09;
38 int n,m;
39 int v[M],Next[M],head[N],e,dp[N][N],du[N];
40 void add(int x,int y){ v[++e]=y; Next[e]=head[x]; head[x]=e;}
41 void dfs(int u,int fa){
42     for (int i=head[u];i;i=Next[i])
43     if (v[i]!=fa){
44         dfs(v[i],u);
45         for (int j=m;j>1;j--){
46             for (int k=1;k<j;k++){
47                 dp[u][j]=min(dp[u][j],dp[u][k]+dp[v[i]][j-k]-2);
48             }
49         }
50     }
51 }
52 int main(){
53     n=read(),m=read();
54     for (int i=1;i<n;i++) {
55         int a=read(),b=read();
56         add(a,b); add(b,a);
57         du[a]++; du[b]++;
58     }
59     for (int i=1;i<=n;i++){
60         dp[i][1]=du[i];
61         for (int j=2;j<=m;j++) 
62             dp[i][j]=inf;
63     }
64     dfs(1,0);
65     int ans=inf;
66     for (int i=1;i<=n;i++)
67         ans=min(ans,dp[i][m]);
68     printf("%d",ans);
69     return 0;
70 }