我最初有一个用于拓扑排序的递归解决方案：
void dfs(int v, bool visited[], node* adjList[], std::stack<int> &myStack) {
visited[v] = true;
node* curr = adjList[v];
while (curr != NULL) {
if(!visited[curr->val]) {
dfs(curr->val, visited, adjList, myStack);
}
curr = curr->next;
}
myStack.push(v);
}
它似乎对我的目的有用。但我无法将其转化为迭代解决方案。这是我的尝试：
void dfs(int v, bool visited[], node* adjList[], std::stack<int> &myStack) {
std::stack<int> recursion;
visited[v] = true;
recursion.push(v);
while( !recursion.empty() ) {
v = recursion.top();
recursion.pop();
node* curr = adjList[v];
myStack.push(v);
while (curr != NULL) {
if(!visited[curr->val]) {
visited[curr->val] = true;
recursion.push(curr->val);
}
curr = …为了练习,我试图让Flask服务器不断地将"Hello"打印到HTML页面的控制台.我现在迷失了如何继续.
目前,我的服务器代码看起来像这样
app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
socketio = SocketIO(app)
@socketio.on('message')
def handle_message(message):
print('Message: ' + message)
send(message)
@socketio.on('json')
def handle_json(json):
send(json, json=True)
@socketio.on('my event')
def handle_my_custom_event(json):
emit('my response', json, broadcast=True)
def hello():
emit('message', {'hello':"Hello"})
@app.route('/')
def index():
return render_template('index.html')
if __name__ == '__main__':
socketio.run(app)
while True:
hello()
虽然我的客户端代码如下所示:
<head>
<script type="text/javascript" charset="utf-8">
var socket = io.connect('http://' + document.domain + ':' + location.port);
socket.on('connect', function() {
socket.emit('connected');
});
socket.on('message', function(data) {
console.log(data);
});
</script>
</head> …这是我在网上找到的一个Java示例:
try{
//use buffering
InputStream file = new FileInputStream("quarks.ser");
InputStream buffer = new BufferedInputStream(file);
ObjectInput input = new ObjectInputStream (buffer);
try{
//deserialize the List
List<String> recoveredQuarks = (List<String>)input.readObject();
//display its data
for(String quark: recoveredQuarks){
System.out.println("Recovered Quark: " + quark);
}
}
finally{
input.close();
}
} catch(ClassNotFoundException ex){
//some exception handling
}
在上面,使用try-finally块在关闭输入之前使用输入执行某些处理有什么好处？换句话说,上面的代码对这样的东西有什么好处:
try{
//use buffering
InputStream file = new FileInputStream("quarks.ser");
InputStream buffer = new BufferedInputStream(file);
ObjectInput input = new ObjectInputStream (buffer);
List<String> recoveredQuarks = (List<String>)input.readObject();
for(String quark: recoveredQuarks){
System.out.println("Recovered Quark: …