关于map

为啥判定一个数是否存在必须用count，直接访问会错啊

e.g.

CPP

map <int, bool> maps[N];
maps[x][y] = 1;

对于这个东西，执行maps[x].count (y)和maps[x][y]得到的结果有时候不一样啊

下面是我遇到问题的完整函数

CPP

void dijkstra ()
{
	while (!q.empty ())
	{
		int u = q.top ().u, dis = q.top ().dis, f = q.top ().from;
		q.pop ();
		if (vis[u].size () >= k || vis[u].count (f)) continue;
		vis[u][f] = 1;
		for (int i = 0; i < (int) g[u].size (); i++)
		{
			int v = g[u][i].first, w = g[u][i].second;
			if (w + dis <= r && vis[v].size () < k && !vis[v].count (f)) {q.push (node {v, w + dis, f});}
		}
	}
}

CPP

void dijkstra ()
{
	while (!q.empty ())
	{
		int u = q.top ().u, dis = q.top ().dis, f = q.top ().from;
		q.pop ();
		if (vis[u].size () >= k || vis[u][f]) continue;
		vis[u][f] = 1;
		for (int i = 0; i < (int) g[u].size (); i++)
		{
			int v = g[u][i].first, w = g[u][i].second;
			if (w + dis <= r && vis[v].size () < k && !vis[v][f]) {q.push (node {v, w + dis, f});}
		}
	}
}

这两个代码为什么效果不一样啊

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