[英]Why is my recursion keep throwing a StackOverflow error?
I am trying to generate a tree, of all the possible states of the 8-N problem , with no duplicates. 我正在尝试生成一个没有重复的,包含8-N 问题的所有可能状态的树。 I can do it on paper but in code I can't. 我可以在纸上做,但不能用代码做。
Here is my recursive function: 这是我的递归函数:
......
...
..
root = new TreeNode(startingState);
visitedStates.add(root.getData().getStateValues());
generateStateSpaceRecursive(root);
}
public void generateStateSpaceRecursive(TreeNode node){
List<TreeNode> nextStatesNodes = getNextStates(node);
for (TreeNode childNode : nextStatesNodes){
if(!stateVisited(childNode.getData().getStateValues())) {
visitedStates.add(childNode.getData().getStateValues());
node.addChild(childNode);
generateStateSpaceRecursive(childNode);
}
}
}
Why would it not stop? 为什么不停止?
Also if I understood the problem correctly it says, 同样,如果我正确理解了问题,它会说:
Implement the following types of search to (try to) solve this problem: depth first, breadth first, iterative deepening, some form of heuristic search. 实施以下类型的搜索以(尝试)解决此问题:深度优先,宽度优先,迭代加深,某种形式的启发式搜索。
But I need the state space first right? 但是我首先需要状态空间吗? Or I can just apply the algorithms and generate the states on the fly? 或者我可以仅应用算法并即时生成状态?
Edit: 编辑:
private List<TreeNode> getNextStates(TreeNode node) {
List<TreeNode> nextStates = new ArrayList<>();
if(agent.canMoveLeft(node)){
nextStates.add(agent.moveLeft(node));
}
if(agent.canMoveRight(node)){
nextStates.add(agent.moveRight(node));
}
if(agent.canMoveUp(node)){
nextStates.add(agent.moveUp(node));
}
if(agent.canMoveDown(node)){
nextStates.add(agent.moveDown(node));
}
return nextStates;
}
Your state is too big to fit the stack. 您的状态太大,无法容纳堆栈。 Test your algorithm: 测试算法:
You should edit generateStateSpaceRecursive: 您应该编辑generateStateSpaceRecursive:
public void generateStateSpaceRecursive(TreeNode node)
{
if(!testGoal)
{
//Goal node is not seen
List<TreeNode> nextStatesNodes = getNextStates(node);
...
}
else
//Goal Node Visited
}
Create new function like this: 创建这样的新功能:
private bool testGoal(TreeNode node)
{
if(node == goalNode) return true;
else return false;
}
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