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bst.cpp
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bst.cpp
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#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
using namespace std;
struct TreeNode {
public:
int val;
TreeNode* left;
TreeNode* right;
TreeNode(int num) {
val=num;
left=NULL;
right=NULL;
}
};
TreeNode* searchBST(TreeNode* root, int val) {
if(root->val==val)return root;
if(root->val>val)return searchBST(root->left, val);
return searchBST(root->right, val);
}
int findCeil(TreeNode* root, int x) {
int ans=root->val;
while(root && ans!=x) {
if(root->val>=x) {
ans=root->val;
root=root->left;
}
else {
root=root->right;
}
}
if(ans<x)return -1;
return ans;
}
int findFloor(TreeNode* root, int x) {
int ans=root->val;
while(root && ans!=x) {
if(root->val<=x) {
ans=root->val;
root=root->right;
}
else {
root=root->left;
}
}
if(ans>x)return -1;
return ans;
}
int minDiff(TreeNode* root, int x) {
int ans=INT_MAX;
while(root && ans!=0) {
ans=min(abs(root->val-x), ans);
if(root->val>=x) {
root=root->left;
}
else {
root=root->right;
}
}
return ans;
}
TreeNode* insertIntoBST(TreeNode* root, int val) {
if(!root)return new TreeNode(val);
TreeNode* ret=root;
while(root) {
if(root->val<val) {
if(!root->right) {
root->right=new TreeNode(val);
break;
}
root=root->right;
}
else {
if(!root->left) {
root->left=new TreeNode(val);
break;
}
root=root->left;
}
}
return ret;
}
TreeNode* helperDeleteNode(TreeNode* root) {
if(!root->right)return root->left;
TreeNode* rightChild=root->left;
while(rightChild->left)rightChild=rightChild->left;
rightChild->left=root->left;
return root->right;
}
TreeNode* deleteNode(TreeNode*& root, int key) {
if(!root)return nullptr;
if(root->val==key)return helperDeleteNode(root);
TreeNode* ret=root;
while(root) {
if(root->val>key) {
if(root->left && root->left->val==key) {
root->left=helperDeleteNode(root->left);
break;
}
root=root->left;
}
else {
if(root->right && root->right->val==key) {
root->right=helperDeleteNode(root->right);
break;
}
root=root->right;
}
}
return ret;
}
void kSmallest(TreeNode* root, int& k, int& ans) {
if(ans!=-1)return;
if(root->left)kSmallest(root->left, k, ans);
k--;
if(k==0)ans=root->val;
else if(root->right)kSmallest(root->right, k, ans);
}
bool isValidBST(TreeNode* root) {
bool l=true, r=true;
if(root->left) {
l=isValidBST(root->left);
if(l) {
TreeNode* temp=root->left;
while(temp->right) {
temp=temp->right;
}
l=root->val>temp->val;
}
}
if(root->right) {
r=isValidBST(root->right);
if(r) {
TreeNode* temp=root->right;
while(temp->left) {
temp=temp->left;
}
r=root->val<temp->val;
}
}
return l&&r;
}
bool isBST(TreeNode* root, long mn=LONG_MIN, long mx=LONG_MAX) {
if(!root)return true;
if(root->val>=mx || root->val<=mn)return false;
return isBST(root->left, mn, root->val) && isBST(root->right, root->val, mx);
}
TreeNode* lcaBST(TreeNode* root, TreeNode* p, TreeNode* q) {
if((root->val-p->val)*(root->val-q->val)<=0)return root;
if(root->val-p->val>0)return lcaBST(root->left, p, q);
return lcaBST(root->right, p, q);
}
TreeNode* bstPreorder(vector<int>& preorder, int end, int curr) {
if(curr>end)return nullptr;
TreeNode* root=new TreeNode(preorder[curr]);
int i=curr+1;
while(i<=end && preorder[i]<=preorder[curr])i++;
root->left=bstPreorder(preorder, i-1, curr+1);
root->right=bstPreorder(preorder, end, i);
return root;
}
TreeNode* BSTPreorder(vector<int>& preorder, int& i, int bound=INT_MAX) {
if(i==preorder.size() || preorder[i]>bound)return nullptr;
TreeNode* root=new TreeNode(preorder[i++]);
root->left=BSTPreorder(preorder, i, root->val);
root->right=BSTPreorder(preorder, i, bound);
return root;
}
void inorderSuccessor(TreeNode* root, int val, int& ans) {
if(!root)return;
if(root->val<=val)inorderSuccessor(root->right, val, ans);
else {
ans=root->val;
inorderSuccessor(root->left, val, ans);
}
}
// void recoverBST(TreeNode* root, int lb=LONG_MIN, int ub=LONG_MAX) {
// if(!root)return;
// if(root->val>ub)swap(root->val);
// recoverBST(root->left, lb, root->val);
// recoverBST(root->left, root->val, ub);
// }
int main() {
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
TreeNode* root=new TreeNode(10);
root->left=new TreeNode(8);
root->right=new TreeNode(17);
root->left->left=new TreeNode(4);
root->left->right=new TreeNode(9);
root->right->left=new TreeNode(12);
root->right->right=new TreeNode(25);
root->left->right->left=new TreeNode(8);
root->left->right->right=new TreeNode(9);
root->left->right->right->left=new TreeNode(10);
return 0;
}