自我感觉良好，也改过一遍，但还是0分……

#include <cstdio>
#include <string.h>
using namespace std;
//---------变量------ 
int map[21][51];
int m, n;
int ans;
bool sta[51];
//--------函数-------
void Scan()
{
	scanf("%d %d", &n, &m);
	for(int i = 1; i <= m; i++)
	{
		int Start, End, Length;
		scanf("%d %d %d", &Start, &End, &Length);
		map[Start][End] = Length;
		map[End][Start] = Length;
		sta[i] = false;
	}
}
void Dfs(int x, int temp)//x为观景台编号
{
	if(temp > ans)
		ans = temp;
	for(int i = 1; i <= m; i++)
	{
		if(i == x)
			continue;
		if(i == x && map[x][i] == map[i][x])
			continue;	
		if(map[x][i] && !sta[i])
		{
			sta[i] = true;
			Dfs(i, temp + map[x][i]);
			sta[i] = false;
		}
	}
	return;
}
int main()
{
	Scan();
	for(int i = 1; i <= m; i++)
	{
		memset(sta, false, sizeof(sta));
		Dfs(i, 0);
	}
	printf("%d", ans);
	return 0;
}