sicily 1024 Magic Island dfs

        这题就是个杯具~~~简单的dfs, WA了无数次，后来发现是因为每次cases忘了重新把vector数组clear掉，晕死~~~

#include<iostream>

#include <vector>

#include <stdio.h>

#include <memory.h>

using namespace std;



struct info

{

	int id;

	int len;

	info(int id, int len)

	{

		this->id = id;

		this->len = len;

	}

	info(){}

};



vector<info> head[10005];

bool isvisit[10005];

int N, K;

int result;

int sum = 0;

void dfs(int, int);



int main()

{

	int x, y, distance;

	while (cin >> N)

	{

		cin >> K;

		sum = 0;

		result = 0;

		memset(isvisit, false, sizeof(isvisit));

		for (int i = 1; i < N; i++)

		{

			scanf("%d%d%d", &x, &y, &distance);



			head[x-1].push_back(info(y-1, distance));

			head[y-1].push_back(info(x-1, distance));

		}

		isvisit[K-1] = true;

		dfs(K-1, 0);

		cout << result << endl;



		for (int i = 0; i < N; i++)

			head[i].clear();

	}

	return 0;

}



void dfs(int begin, int sum)

{

	

	for (int i = 0; i < head[begin].size(); i++)

	{

		if (!isvisit[head[begin][i].id])

		{

			isvisit[head[begin][i].id] = true;

			sum += head[begin][i].len;

			result = max(result, sum);

			dfs(head[begin][i].id, sum);	

			sum -= head[begin][i].len;

			isvisit[head[begin][i].id] = false;

		}

	}

}