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codingfarm

BST(Binary Search Tree) 본문

Algorithm & Data structure/이론

BST(Binary Search Tree)

scarecrow1992 2020. 9. 6. 16:59
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#include<iostream>
 
using namespace std;
 
class TreeNode {
public:
    int value;
    TreeNode *left, *right, *parent;
};
 
TreeNode treeNodePool[1500000];
int treeNodePoolIndex;
 
TreeNode* NewTreeNode() {
    int tmp = treeNodePoolIndex;
    treeNodePoolIndex++;
    treeNodePool[tmp].value = -1;
    treeNodePool[tmp].left = 0;
    treeNodePool[tmp].right = 0;
    treeNodePool[tmp].parent = 0;
 
    return &treeNodePool[tmp];
}
 
class Tree {
public:
    TreeNode * root;
 
    void Init() {
        root = 0;
    }
 
    void Insert(int value) {
        TreeNode *parent = 0, *finder = root, **p = 0;
 
        while (1) {
            if (finder == 0) {
                TreeNode *newNode = NewTreeNode();
                newNode->value = value;
                if (root == 0) {
                    root = newNode;
                }
                else {
                    *p = newNode;
                    newNode->parent = parent;
                }
                return;
            }
 
            parent = finder;
            if (value >= finder->value) {
                p = &parent->right;
                finder = finder->right;
            }
            else {
                p = &parent->left;
                finder = finder->left;
            }
        }
    }
 
    TreeNode* Find(int value) {
        TreeNode *finder = root;
        while (1) {
            if (finder == 0)                
                return 0;
            
            if (finder->value == value)
                return finder;
 
            if (value > finder->value)
                finder = finder->right;
            else
                finder = finder->left;
        }
    }
 
    TreeNode* Erase(int value) {
        TreeNode *eraser = Find(value);
        
        if (eraser == 0)
            return 0;
        
        TreeNode *parent = eraser->parent, **p = 0;
        if (eraser != root) {
            if (parent->right == eraser)
                p = &parent->right;
            else if (parent->left == eraser)
                p = &parent->left;
        }
 
        if (eraser->left == 0 && eraser->right == 0) {
            //자식이 하나도 없을 경우
            if (eraser == root)
                root = 0;
            else
                *p = 0;
        }
        else if (eraser->left != 0 && eraser->right == 0) {
            //자식이 왼쪽에만 있을 경우
            if (eraser == root) {
                root = eraser->left;
                eraser->left->parent = 0;
            }
            else {
                *p = eraser->left;
                eraser->left->parent = parent;
            }
        }
        else if (eraser->left == 0 && eraser->right != 0) {
            //자식이 오른쪽에만 있을 경우
            if (eraser == root) {
                root = eraser->right;
                eraser->right->parent = 0;
            }
            else {
                *p = eraser->right;
                eraser->right->parent = parent;
            }
        }
        else if (eraser->left != 0 && eraser->right != 0) {
            //자식이 양쪽에 있을 경우
            TreeNode *finder = eraser->left;
            while (1) {
                if (finder->right == 0)
                    break;
                finder = finder->right;
            }
        
            Erase(finder->value);
 
            if (eraser == root) {
                root = finder;
                finder->parent = 0;
            }
            else {
                *p = finder;
                finder->parent = parent;
            }
 
            finder->left = eraser->left;
            finder->right = eraser->right;
 
            if (eraser->left != 0)
                finder->left->parent = finder;
            
            if (eraser->right != 0)
                finder->right->parent = finder;
        }
    }
};
 
Tree tree;
 
void Init() {
    treeNodePoolIndex = 0;
    tree.Init();
}
 
 
int main(void) {
    Init();
 
    int N;
    cin >> N;
    int input;
    for (int i = 0; i < N; i++) {
        cin >> input;
        tree.Insert(input);
    }
 
    for (int i = 0; i < N; i++) {
        cin >> input;
        tree.Erase(input);
    }
 
    return 0;
}
 
/*
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*/
cs
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