hdu 4616 Game

树dp，学了一招，以边进行dp

#include <stdio.h>
#include <vector>
#include <string.h>
using namespace std;
#define MAXN 50010
int trap[MAXN], gift[MAXN], n, c, ans;
int dp[MAXN<<1][5], head[MAXN], cnt;
struct _edge
{
int u, v, next;
_edge(int uu = 0, int vv = 0, int nn = 0):u(uu),v(vv),next(nn){}
}edge[MAXN<<1];
void add (int u, int v)
{
edge[cnt] = _edge(u,v,head[u]);
memset(dp[cnt], -1, 20);
head[u] = cnt++;
}
int dfs(int dx, int tp)
{
if (tp == c ) return 0;
if (~dp[dx][tp]) return dp[dx][tp];
int u = edge[dx].u;
int v = edge[dx].v;
int res = gift[v];
int a = tp + trap[v];
for (int i = head[v]; ~i; i = edge[i].next)
{
if (edge[i].v == u) continue;
res = max(res, gift[v]+dfs(i, a));
}
return dp[dx][tp] = res;
}
int main()
{
#ifdef __GNUC__
freopen ( "in.txt", "r", stdin );
#endif // __GNUC__
int t;
scanf("%d", &t);
while (t--)
{
scanf("%d%d", &n, &c);
for (int i = 0; i< n; ++i)
{
scanf("%d%d", &gift[i], &trap[i]);
head[i] = -1;
}
cnt = 0;
for (int i = 1; i< n; ++i)
{
int a, b;
scanf("%d%d", &a, &b);
add(a, b);
add(b, a);
}
ans = 0;
for (int i = 0; i< cnt; ++i)
{
int u = edge[i].u;
ans = max(ans, gift[u]+dfs(i,trap[u]));
}
printf("%d\n", ans);
}
return 0;
}