/**

 We are given the head node root of a binary tree, where additionally every node's value is either a 0 or a 1.

 Return the same tree where every subtree (of the given tree) not containing a 1 has been removed.

 (Recall that the subtree of a node X is X, plus every node that is a descendant of X.)

 Example 1:
 Input: [1,null,0,0,1]
 Output: [1,null,0,null,1]

 Explanation:
 Only the red nodes satisfy the property "every subtree not containing a 1".
 The diagram on the right represents the answer.


 Example 2:
 Input: [1,0,1,0,0,0,1]
 Output: [1,null,1,null,1]



 Example 3:
 Input: [1,1,0,1,1,0,1,0]
 Output: [1,1,0,1,1,null,1]



 Note:

 The binary tree will have at most 100 nodes.
 The value of each node will only be 0 or 1.

 */

public class Binary_Tree_Pruning {

    /**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     int val;
     *     TreeNode left;
     *     TreeNode right;
     *     TreeNode(int x) { val = x; }
     * }
     */
    class Solution {
        public TreeNode pruneTree(TreeNode root) {
            if (root == null) {
                return root;
            }

            root.left = pruneTree(root.left);
            root.right = pruneTree(root.right);

            // leaf node
            if (root.left == null && root.right == null) {
                if (root.val == 0) {
                    return null;
                } else {
                    return root;
                }
            }

            return root;
        }
    }
}

############

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public TreeNode pruneTree(TreeNode root) {
        if (root == null) {
            return null;
        }
        root.left = pruneTree(root.left);
        root.right = pruneTree(root.right);
        if (root.val == 0 && root.left == null && root.right == null) {
            return null;
        }
        return root;
    }
}

// OJ: https://leetcode.com/problems/binary-tree-pruning/
// Time: O(N)
// Space: O(logN)
class Solution {
public:
    TreeNode* pruneTree(TreeNode* root) {
        if (!root) return NULL;
        root->left = pruneTree(root->left);
        root->right = pruneTree(root->right);
        return root->left || root->right || root->val ? root : NULL;
    }
};

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def pruneTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        if root is None:
            return None
        root.left = self.pruneTree(root.left)
        root.right = self.pruneTree(root.right)
        if root.val == 0 and root.left is None and root.right is None:
            return None
        return root

############

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def pruneTree(self, root):
        """
        :type root: TreeNode
        :rtype: TreeNode
        """
        if not root: return
        root.left = self.pruneTree(root.left)
        root.right = self.pruneTree(root.right)
        if not root.left and not root.right and root.val == 0:
            return None
        return root

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func pruneTree(root *TreeNode) *TreeNode {
	if root == nil {
		return nil
	}
	root.Left = pruneTree(root.Left)
	root.Right = pruneTree(root.Right)
	if root.Val == 0 && root.Left == nil && root.Right == nil {
		return nil
	}
	return root
}

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */

function pruneTree(root: TreeNode | null): TreeNode | null {
    if (root == null) {
        return root;
    }
    root.left = pruneTree(root.left);
    root.right = pruneTree(root.right);
    if (root.val == 0 && root.left == null && root.right == null) {
        return null;
    }
    return root;
}

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {TreeNode}
 */
var pruneTree = function (root) {
    if (!root) return null;
    root.left = pruneTree(root.left);
    root.right = pruneTree(root.right);
    if (root.val == 0 && !root.left && !root.right) {
        return null;
    }
    return root;
};

// Definition for a binary tree node.
// #[derive(Debug, PartialEq, Eq)]
// pub struct TreeNode {
//   pub val: i32,
//   pub left: Option<Rc<RefCell<TreeNode>>>,
//   pub right: Option<Rc<RefCell<TreeNode>>>,
// }
//
// impl TreeNode {
//   #[inline]
//   pub fn new(val: i32) -> Self {
//     TreeNode {
//       val,
//       left: None,
//       right: None
//     }
//   }
// }
use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
    pub fn prune_tree(root: Option<Rc<RefCell<TreeNode>>>) -> Option<Rc<RefCell<TreeNode>>> {
        if root.is_none() {
            return None;
        }

        let root = root.unwrap();
        let left = Self::prune_tree(root.borrow_mut().left.take());
        let right = Self::prune_tree(root.borrow_mut().right.take());
        if root.borrow().val == 0 && left.is_none() && right.is_none() {
            return None;
        }

        root.borrow_mut().left = left;
        root.borrow_mut().right = right;
        Some(root)
    }
}

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public TreeNode pruneTree(TreeNode root) {
        if (root == null)
            return root;
        Map<TreeNode, TreeNode> childParentMap = new HashMap<TreeNode, TreeNode>();
        List<TreeNode> nodesList = new ArrayList<TreeNode>();
        Queue<TreeNode> queue = new LinkedList<TreeNode>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            TreeNode node = queue.poll();
            nodesList.add(node);
            TreeNode left = node.left, right = node.right;
            if (left != null) {
                childParentMap.put(left, node);
                queue.offer(left);
            }
            if (right != null) {
                childParentMap.put(right, node);
                queue.offer(right);
            }
        }
        for (int i = nodesList.size() - 1; i >= 0; i--) {
            TreeNode node = nodesList.get(i);
            if (node.val == 0) {
                if (node.left == null && node.right == null) {
                    TreeNode parent = childParentMap.get(node);
                    if (parent != null) {
                        if (node == parent.left)
                            parent.left = null;
                        else
                            parent.right = null;
                    } else {
                        root = null;
                        break;
                    }
                }
            }
        }
        return root;
    }
}

############

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public TreeNode pruneTree(TreeNode root) {
        if (root == null) {
            return null;
        }
        root.left = pruneTree(root.left);
        root.right = pruneTree(root.right);
        if (root.val == 0 && root.left == null && root.right == null) {
            return null;
        }
        return root;
    }
}

// OJ: https://leetcode.com/problems/binary-tree-pruning/
// Time: O(N)
// Space: O(logN)
class Solution {
public:
    TreeNode* pruneTree(TreeNode* root) {
        if (!root) return NULL;
        root->left = pruneTree(root->left);
        root->right = pruneTree(root->right);
        return root->left || root->right || root->val ? root : NULL;
    }
};

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def pruneTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        if root is None:
            return None
        root.left = self.pruneTree(root.left)
        root.right = self.pruneTree(root.right)
        if root.val == 0 and root.left is None and root.right is None:
            return None
        return root

############

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def pruneTree(self, root):
        """
        :type root: TreeNode
        :rtype: TreeNode
        """
        if not root: return
        root.left = self.pruneTree(root.left)
        root.right = self.pruneTree(root.right)
        if not root.left and not root.right and root.val == 0:
            return None
        return root

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func pruneTree(root *TreeNode) *TreeNode {
	if root == nil {
		return nil
	}
	root.Left = pruneTree(root.Left)
	root.Right = pruneTree(root.Right)
	if root.Val == 0 && root.Left == nil && root.Right == nil {
		return nil
	}
	return root
}

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */

function pruneTree(root: TreeNode | null): TreeNode | null {
    if (root == null) {
        return root;
    }
    root.left = pruneTree(root.left);
    root.right = pruneTree(root.right);
    if (root.val == 0 && root.left == null && root.right == null) {
        return null;
    }
    return root;
}

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {TreeNode}
 */
var pruneTree = function (root) {
    if (!root) return null;
    root.left = pruneTree(root.left);
    root.right = pruneTree(root.right);
    if (root.val == 0 && !root.left && !root.right) {
        return null;
    }
    return root;
};

// Definition for a binary tree node.
// #[derive(Debug, PartialEq, Eq)]
// pub struct TreeNode {
//   pub val: i32,
//   pub left: Option<Rc<RefCell<TreeNode>>>,
//   pub right: Option<Rc<RefCell<TreeNode>>>,
// }
//
// impl TreeNode {
//   #[inline]
//   pub fn new(val: i32) -> Self {
//     TreeNode {
//       val,
//       left: None,
//       right: None
//     }
//   }
// }
use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
    pub fn prune_tree(root: Option<Rc<RefCell<TreeNode>>>) -> Option<Rc<RefCell<TreeNode>>> {
        if root.is_none() {
            return None;
        }

        let root = root.unwrap();
        let left = Self::prune_tree(root.borrow_mut().left.take());
        let right = Self::prune_tree(root.borrow_mut().right.take());
        if root.borrow().val == 0 && left.is_none() && right.is_none() {
            return None;
        }

        root.borrow_mut().left = left;
        root.borrow_mut().right = right;
        Some(root)
    }
}

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