【URAL 1018】Binary Apple Tree

http://vjudge.net/problem/17662

loli蜜汁(面向高一)树形dp水题

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

struct nodeTreeDP {
	struct node {int nxt, to, w;} E[203];
	int n, q, cnt, point[103], apple[103], left[103], right[103], f[103][103], size[103];
	nodeTreeDP() {
		cnt = 0;
		memset(E, 0, sizeof(E));
		memset(f, 0, sizeof(f));
		memset(left, 0, sizeof(left));
		memset(right, 0, sizeof(right));
		memset(point, 0, sizeof(point));
		memset(apple, 0, sizeof(apple));
	}

	void ins(int u, int v, int w) {E[++cnt] = (node) {point[u], v, w}; point[u] = cnt;}

	void dfs(int x, int fa) {
		if (x == 0) return;
		for(int i = point[x]; i; i = E[i].nxt)
			if (E[i].to != fa) {
				apple[E[i].to] = E[i].w;
				if (!left[x]) left[x] = E[i].to;
				else right[left[x]] = E[i].to;
			}
		dfs(right[x], fa); dfs(left[x], x);
		size[x] = size[left[x]] + size[right[x]] + 1;
	}

	void TreeDP(int x) {
		if (x == 0) return;
		TreeDP(right[x]); TreeDP(left[x]);

		int tot = size[x], rightnum;

		for(int top = 0; top <= tot; ++top) {
			f[x][top] = max(f[x][top], f[right[x]][top]);
			for(int leftnum = 1; leftnum <= top; ++leftnum) {
				rightnum = top - leftnum;
				f[x][top] = max(f[x][top], f[left[x]][leftnum - 1] + apple[x] + f[right[x]][rightnum]);
			}
		}
	}

	void ansit() {
		TreeDP(left[1]);
		printf("%d\n", f[left[1]][q]);
	}
} *T;

int main() {
	T = new nodeTreeDP;
	scanf("%d%d", &T->n, &T->q);
	int u, v, w;
	for(int i = 1; i < T->n; ++i) {
		scanf("%d%d%d", &u, &v, &w);
		T->ins(u, v, w);
		T->ins(v, u, w);
	}
	T->dfs(1, 0);
	T->ansit();
	return 0;
}