Sicily 1024. Magic Island

/*
树的遍历，寻找最深的节点
注意在初始化的时候得清理所有的空间
*/
/*
Run Time: 0.35secs
Run Memory: 1296KB
*/

#include <iostream>
#include <vector>

using namespace std;

typedef struct Bridge{
int dest;    //该桥目的地
int id;      //该桥id，用于标识
int length;  //长度

Bridge(int a, int b, int c){
dest = a;
id = b;
length = c;
}
};

int N; //city数,1-10000
int K; //首都位置,1-N
vector<Bridge> map[10001];    //存储着整个map，共有10000个city，同一条桥会被双向存储，走的时候不走回头路即可
int MaxLength;

void walk(int father, int now, int length){
for(int i=0; i<map[now].size(); i++){
if(map[now][i].dest != father){
int bufChild = map[now][i].dest;
int newLength = length+map[now][i].length;
if(newLength > MaxLength)
MaxLength = newLength;

walk(now, bufChild, newLength);
}
}
}

int main()
{
while (cin>>N && N){
cin >> K;
//仅需清理需要使用的范围
for(int i=0; i<=N; i++)
if(map[i].size() != 0)
map[i].clear();
MaxLength = 0;

int X, Y, D;
for(int i=0; i<N-1; i++){
cin >> X >> Y >> D;
Bridge buf_1(Y, i, D);
map[X].push_back(buf_1);

Bridge buf_2(X, i, D);
map[Y].push_back(buf_2);
}

walk(-1, K, 0);

cout << MaxLength << endl;
}

return 0;
}