poj 1947 树形背包
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重做这道题
http://blog.csdn.net/woshi250hua/article/details/7632785
http://blog.csdn.net/shuangde800/article/details/10150305
http://blog.csdn.net/alps233/article/details/51190997
#include <iostream> #include <string> #include <cstring> #include <cstdlib> #include <cstdio> #include <cmath> #include <algorithm> #include <stack> #include <queue> #include <cctype> #include <vector> #include <iterator> #include <set> #include <map> #include <sstream> using namespace std; #define mem(a,b) memset(a,b,sizeof(a)) #define pf printf #define sf scanf #define spf sprintf #define pb push_back #define debug printf("!\n") #define MAXN 500+5 #define MAX(a,b) a>b?a:b #define blank pf("\n") #define LL long long #define ALL(x) x.begin(),x.end() #define INS(x) inserter(x,x.begin()) #define pqueue priority_queue #define INF 0x3f3f3f3f #define ls (rt<<1) #define rs (rt<<1|1) int n,m; int head[MAXN],vis[MAXN],ptr=1; int dp[MAXN][MAXN],num[MAXN]; struct node{int y,next,val;}tree[MAXN<<2]; void init() { mem(head,-1); mem(vis,0); mem(dp,INF); mem(num,0); ptr = 1; } void add(int son,int fa) { tree[ptr].y=son; tree[ptr].next=head[fa]; head[fa]=ptr++; } void dfs(int rt) { num[rt] = vis[rt] = 1; int tot = 0; for(int i = head[rt];i!=-1;i=tree[i].next) { int y = tree[i].y; if(vis[y]) continue; dfs(y); tot++; num[rt]+=num[y]; } dp[rt][1] = tot; for(int i = head[rt];i!=-1;i=tree[i].next) { int y = tree[i].y; for(int j = num[rt];j>1;j--) { for(int k = 1;k<j;k++) { if(dp[rt][j-k]!=INF && dp[y][k]!=INF); dp[rt][j] = min(dp[rt][j],dp[rt][j-k]+dp[y][k]-1); } } } } int main() { int i,j,k=1; while(~sf("%d%d",&n,&m)) { init(); for(i=1;i<n;i++) { int x,y; sf("%d%d",&x,&y); add(x,y); add(y,x); } dfs(1); int ans = INF; for(i=1;i<=n;i++) { if(i==1) ans = min(dp[i][m],ans); else ans = min(dp[i][m]+1,ans); } pf("%d\n",ans); } }
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