I get Following error on running the code below for tree(2,2,2) on leetcode:
AddressSanitizer:DEADLYSIGNAL
==31==ERROR: AddressSanitizer: stack-overflow on address 0x7ffe3ba89ff8 (pc 0x000000372df9 bp 0x7ffe3ba8a010 sp 0x7ffe3ba8a000 T0)
==31==ABORTING
My code is given below:
class Solution {
public:
bool isValidBST(TreeNode* root) {
TreeNode* cur=root;
while(cur){
cout<<cur->val<<endl;
if(!cur->left) {
if(!cur->right) return 1;
int a=cur->val,b=cur->right->val;
if(a>=b )
return false;
cur=cur->right;
}
else{
TreeNode* prev=cur->left;
while(prev->right && prev->right!=cur)
prev=prev->right;
if(prev->right==NULL){
prev->right=cur;
cur=cur->left;
}
else{
prev->right=0;
if(cur->val>=cur->right->val) return 0;
cur=cur->right;
}
}
}
return 1;
}
};
Related
i have the following grammar and i would like to create the First & follow table. if i have a case that the first of non terminal is epsilon should i take also all the terminals that came after this non terminal from is rule?
S-> ABC
A->Aa/aB
B->Bb/epsilon
C->Cc/epsilon
and my question is:
in the first of C i need to get First(C) = {epsilon,c) and First(B) = {epsilon,b)?
i got the following results but still i think i have problems:
|first|follow
S |a |$
A |a |a
B |eps,b|b,a,$
C |eps,c|$
Finding the FIRST and Follow of a Grammar written in txt FILE:
#include<stdio.h>
#include<string.h>
#define size 10
int i,j,l,m,n=0,o,p,nv,z=0,x=0;
char str[size],temp,temp2[size],temp3[20],*ptr;
struct prod
{
char left_of_non_term[size],right_of_nonTerm[size][size],first[size],fol[size];
int n;
}pro[size];
int main()
{
FILE *f;
for(i=0;i<size;i++)
pro[i].n=0;
f=fopen("lab6.txt","r");
while(!feof(f))
{
fscanf(f,"%s",pro[n].left_of_non_term);
if(n>0)
{
if( strcmp(pro[n].left_of_non_term,pro[n-1].left_of_non_term) == 0 )
{
pro[n].left_of_non_term[0]='\0';
fscanf(f,"%s",pro[n-1].right_of_nonTerm[pro[n-1].n]);
pro[n-1].n++;
continue;
}
}
fscanf(f,"%s",pro[n].right_of_nonTerm[pro[n].n]);
pro[n].n++;
n++;
}
printf("\nGiven Grammar");
printf("\n-------------\n");
for(i=0;i<n;i++)
for(j=0;j<pro[i].n;j++)
printf("%s = %s\n",pro[i].left_of_non_term,pro[i].right_of_nonTerm[j]);
pro[0].first[0]='#';
for(i=0;i<n;i++)
{
for(j=0;j<pro[i].n;j++)
{
if( pro[i].right_of_nonTerm[j][0]<65 || pro[i].right_of_nonTerm[j][0]>90 )
{
pro[i].first[strlen(pro[i].first)]=pro[i].right_of_nonTerm[j][0];
}
else if( pro[i].right_of_nonTerm[j][0]>=65 && pro[i].right_of_nonTerm[j][0]<=90 )
{
temp=pro[i].right_of_nonTerm[j][0];
if(temp=='S')
pro[i].first[strlen(pro[i].first)]='#';
findter();
}
}
}
printf("-------------");
printf("\n\nFIRST\n");
for(i=0;i<n;i++)
{
printf("\n%s -> { ",pro[i].left_of_non_term);
for(j=0;j<strlen(pro[i].first);j++)
{
for(l=j-1;l>=0;l--)
if(pro[i].first[l]==pro[i].first[j])
break;
if(l==-1)
printf("%c ",pro[i].first[j]);
}
printf("}");
}
for(i=0;i<n;i++)
temp2[i]=pro[i].left_of_non_term[0];
pro[0].fol[0]='$';
for(i=0;i<n;i++)
{
for(l=0;l<n;l++)
{
for(j=0;j<pro[i].n;j++)
{
ptr=strchr(pro[l].right_of_nonTerm[j],temp2[i]);
if( ptr )
{
p=ptr-pro[l].right_of_nonTerm[j];
if(pro[l].right_of_nonTerm[j][p+1]>=65 && pro[l].right_of_nonTerm[j][p+1]<=90)
{
for(o=0;o<n;o++)
if(pro[o].left_of_non_term[0]==pro[l].right_of_nonTerm[j][p+1])
strcat(pro[i].fol,pro[o].first);
}
else if(pro[l].right_of_nonTerm[j][p+1]=='\0')
{
temp=pro[l].left_of_non_term[0];
if(pro[l].right_of_nonTerm[j][p]==temp)
continue;
if(temp=='S')
strcat(pro[i].fol,"$");
findfol();
}
else
pro[i].fol[strlen(pro[i].fol)]=pro[l].right_of_nonTerm[j][p+1];
}
}
}
}
printf("\n\n\n");
for(i=0;i<n;i++)
{
printf("\nFOLLOW (%s) -> { ",pro[i].left_of_non_term);
for(j=0;j<strlen(pro[i].fol);j++)
{
for(l=j-1;l>=0;l--)
if(pro[i].fol[l]==pro[i].fol[j])
break;
if(l==-1)
printf("%c",pro[i].fol[j]);
}
printf(" }");
}
printf("\n");
//getch();
}
void findter()
{
int k,t;
for(k=0;k<n;k++)
{
if(temp==pro[k].left_of_non_term[0])
{
for(t=0;t<pro[k].n;t++)
{
if( pro[k].right_of_nonTerm[t][0]<65 || pro[k].right_of_nonTerm[t][0]>90 )
pro[i].first[strlen(pro[i].first)]=pro[k].right_of_nonTerm[t][0];
else if( pro[k].right_of_nonTerm[t][0]>=65 && pro[k].right_of_nonTerm[t][0]<=90 )
{
temp=pro[k].right_of_nonTerm[t][0];
if(temp=='S')
pro[i].first[strlen(pro[i].first)]='#';
findter();
}
}
break;
}
}
}
void findfol()
{
int k,t,p1,o1,chk;
char *ptr1;
for(k=0;k<n;k++)
{
chk=0;
for(t=0;t<pro[k].n;t++)
{
ptr1=strchr(pro[k].right_of_nonTerm[t],temp);
if( ptr1 )
{
p1=ptr1-pro[k].right_of_nonTerm[t];
if(pro[k].right_of_nonTerm[t][p1+1]>=65 && pro[k].right_of_nonTerm[t][p1+1]<=90)
{
for(o1=0;o1<n;o1++)
if(pro[o1].left_of_non_term[0]==pro[k].right_of_nonTerm[t][p1+1])
{
strcat(pro[i].fol,pro[o1].first);
chk++;
}
}
else if(pro[k].right_of_nonTerm[t][p1+1]=='\0')
{
temp=pro[k].left_of_non_term[0];
if(pro[l].right_of_nonTerm[j][p]==temp)
continue;
if(temp=='S')
strcat(pro[i].fol,"$");
findfol();
chk++;
}
else
{
pro[i].fol[strlen(pro[i].fol)]=pro[k].right_of_nonTerm[t]
[p1+1];
chk++;
}
}
}
if(chk>0)
break;
}
}
Also Make a text File named it lab6.txt . and put grammers like below
S ABCDE
A a|0
B b|0
C c
D d|0
E e|0
Here space after NonTerminal Indicates the -> this sign and 0 indicates epsilon.
I'm trying to code that converts infix expressions to postfix expressions. Currently, the program works correctly if I enter for e.g "5+6" it will output the correct answer which is "5 6 +". The problem occurs when I enter more than one operator for e.g "5+6-3", it outputs and incorrect answer "+3-". Can someone please point out where I'm making the error ? Thanks, in advance !
void main(){
Stack *s = new Stack;
string input;
cout <<"Enter Expression"<<endl;
cin>>input;
InfixToPostfix(input);
system("PAUSE");
}
string InfixToPostfix(string input){
Stack *S = new Stack();
string postfix = "";
for (int i=0; i < input.length();i++){
if (input[i]== ' '||input[i]==',') continue;
else if (IsOperator(input[i]))
{
while(!S->IsStackEmpty() && S->StackTop() != '(' && HasHigherPrecedence(S->StackTop(),input[i]))
{
postfix=S->StackTop();
S->Pop();
}
S->Push(input[i]);
}
else if(IsOperand(input[i]))
{
postfix +=input[i];
}
else if (input[i] == '(')
{
S->Push(input[i]);
}
else if (input[i]==')')
{
while(!S->IsStackEmpty() && S->StackTop() != '('){
postfix += S->StackTop();
S->Pop();
}
S->Pop();
}
}
while(!S->IsStackEmpty()){
postfix +=S->StackTop();
S->Pop();
}
cout <<""<<postfix;
return postfix;
}
bool IsOperand(char C)
{
if(C>= '0' && C<= '9') return true;
if(C>= 'a' && C<= 'z') return true;
if(C>= 'A' && C<= 'Z') return true;
return false;
}
bool IsOperator(char C)
{
if(C=='+' || C== '-' || C =='*' || C == '/' ||C == '$')
{
return true;
}else{
return false;
}
}
int IsRightAssociative(char op)
{
if(op=='$'){
return true;
}else{
return false;
}
}
int GetOperatorWeight(char op){
int weight = -1;
switch(op)
{
case'+':
case '-':
weight=1;
break;
case '*':
case '/':
weight=2;
break;
case '$':
weight=3;
break;
}
return weight;
}
int HasHigherPrecedence ( char op1, char op2)
{
int op1Weight= GetOperatorWeight(op1);
int op2Weight = GetOperatorWeight(op2);
if(op1Weight == op2Weight)
{
if(IsRightAssociative(op1))
{
return false;
}else{
return true;
}
return op1Weight > op2Weight ? true:false;
}
}
One suggestion: use a tree, rather than a stack, as an intermediate data structure. Let the operator with lowest precedence be the root of the tree and build it recursively from there. Then walk through the tree from left to right, again recursively, to generate the postfix version. That way, you can also keep track of the maximum stack depth for the postfix version, which can be important as many hand-held RPN calculators, for example, have very limited stack depths.
I tried binary tree data structure but found it to be not working and giving an error. Please correct my code. Thanks!
It gives warning but with the inputs in main it stops running .
#include<stdlib.h>
#include<stdio.h>
typedef struct
{
int item;
struct node * leftc;
struct node * rightc;
}node;
void create(int key, node **tree )
{
if(*tree ==0)
{
(*tree)= (node *)malloc(sizeof(node *));
(*tree)->item=key;
(*tree)->leftc=((*tree)->rightc)=NULL;
}
else
{
if(key >= (*tree)->item )
{
create(key, &((*tree)->rightc));
}
else if(key<(*tree)->item)
{
create(key, &((*tree)->leftc));
}
}
}
node * search(int key, node * tree)
{
if(tree !=NULL)
{
if(key == tree->item)
return tree;
else if(key > tree->item)
search(key, tree->rightc);
else
search(key, tree->leftc);
}
return NULL;
}
void cut(node * tree)
{
if(tree != NULL)
{
cut(tree->leftc);
cut(tree->rightc);
free(tree);
}
}
void print_preorder(node * tree)
{
if (tree) {
printf("%d\n",tree->item);
print_preorder(tree->leftc);
print_preorder(tree->rightc);
}
}
int main()
{
node * root=NULL;
create(9,&root);
create(16,&root);
create(24,&root);
create(6,&root);
return 0;
}
Change
typedef struct
{
int item;
struct node * leftc;
struct node * rightc;
}node;
to
typedef struct node
{
int item;
struct node * leftc;
struct node * rightc;
}node;
Within your structure you refer to 'struct node' so you need the name in order for it to properly reference itself. Of course, after the typedef then you can just refer to it as node.
The test program compiled and ran fine with the code given otherwise.
I know this doesn't answer your question about the error, but I noticed a major problem with your search() function. You only return the node you're looking for if it's the first one that is put into the function. The recursive calls to search() do not return anything. The function should look something like this:
node * search(int key, node * tree)
{
if (tree !=NULL)
{
if (key == tree->item) {
return tree;
} else if (key > tree->item) {
return search(key, tree->rightc);
} else if (key < tree->item) {
return search(key, tree->leftc);
}
}
return NULL;
}
Also, in your create() function, did you mean to check if (*tree == NULL) instead of if (*tree == 0)?
I'm trying to figure out how to write a custom FindElement routine in Selenium 2.0 WebDriver. The idea would be something like this:
driver.FindElement(By.Method( (ISearchContext) => {
/* examine search context logic here... */ }));
The anonymous method would examine the ISearchContext and return True if it matches; False otherwise.
I'm digging through the Selenium code, and getting a bit lost. It looks like the actual By.* logic is carried out server-side, not client side. That seems to be complicating matters.
Any suggestions?
I do a multi-staged search. I have a method that performs a try catch and then a method that gets the element. In theory you could do a try catch until instead of this way but I like this way better because of my setup.
public bool CheckUntil(IWebDriver driver, string selectorType, string selectorInfo)
{
int Timer = 160;
bool itemFound = false;
for (int i = 0; i < Timer; i++)
if(itemFound)
{
i = 0
}
else
{
Thread.Sleep(500);
if(selectorType.ToLower() == "id" && TryCatch(driver, selectorType, selectorInfo))
{
if(driver.FindElement(By.Id(selectorInfo).Displayed)
{
itemFound = true;
}
}
else if(selectorType.ToLower() == "tagname" && TryCatch(driver, selectorType, selectorInfo))
{
if(driver.FindElement(By.TagName(selectorInfo).Displayed)
{
itemFound = true;
}
}
}
return itemFound;
}
Here's my try catch method you can add as many different types as you want id, cssselector, xpath, tagname, classname, etc.
public bool TryCatch(IWebDriver driver, string selectorType, string selectorInfo)
{
bool ElementFound = false;
try
{
switch(selectorType)
{
case "id":
driver.FindElement(By.Id(selectorInfo);
break;
case "tagname":
driver.FindElement(By.TagName(selectorInfo);
break;
}
ElementFound = truel
}
catch
{
ElementFound = false;
}
return ElementFound;
}
Ok, I figured out how to do this. I'm leveraging driver.ExecuteScript() to run custom js on the webdriver. It looks a bit like this:
function elementFound(elem) {
var nodeType = navigator.appName == ""Microsoft Internet
Explorer"" ? document.ELEMENT_NODE : Node.ELEMENT_NODE;
if(elem.nodeType == nodeType)
{
/* Element identification logic here */
}
else { return false; }
}
function traverseElement(elem) {
if (elementFound(elem) == true) {
return elem;
}
else {
for (var i = 0; i < elem.childNodes.length; i++) {
var ret = traverseElement(elem.childNodes[i]);
if(ret != null) { return ret; }
}
}
}
return traverseElement(document);
I am trying to follow Trees tutorial at: http://cslibrary.stanford.edu/110/BinaryTrees.html
Here is the code I have written so far:
package trees.bst;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
/**
*
* #author sachin
*/
public class BinarySearchTree {
Node root = null;
class Node {
Node left = null;
Node right = null;
int data = 0;
public Node(int data) {
this.left = null;
this.right = null;
this.data = data;
}
}
public void insert(int data) {
root = insert(data, root);
}
public boolean lookup(int data) {
return lookup(data, root);
}
public void buildTree(int numNodes) {
for (int i = 0; i < numNodes; i++) {
int num = (int) (Math.random() * 10);
System.out.println("Inserting number:" + num);
insert(num);
}
}
public int size() {
return size(root);
}
public int maxDepth() {
return maxDepth(root);
}
public int minValue() {
return minValue(root);
}
public int maxValue() {
return maxValue(root);
}
public void printTree() { //inorder traversal
System.out.println("inorder traversal:");
printTree(root);
System.out.println("\n--------------");
}
public void printPostorder() { //inorder traversal
System.out.println("printPostorder traversal:");
printPostorder(root);
System.out.println("\n--------------");
}
public int buildTreeFromOutputString(String op) {
root = null;
int i = 0;
StringTokenizer st = new StringTokenizer(op);
while (st.hasMoreTokens()) {
String stNum = st.nextToken();
int num = Integer.parseInt(stNum);
System.out.println("buildTreeFromOutputString: Inserting number:" + num);
insert(num);
i++;
}
return i;
}
public boolean hasPathSum(int pathsum) {
return hasPathSum(pathsum, root);
}
public void mirror() {
mirror(root);
}
public void doubleTree() {
doubleTree(root);
}
public boolean sameTree(BinarySearchTree bst) { //is this tree same as another given tree?
return sameTree(this.root, bst.getRoot());
}
public void printPaths() {
if (root == null) {
System.out.println("print path sum: tree is empty");
}
List pathSoFar = new ArrayList();
printPaths(root, pathSoFar);
}
///-------------------------------------------Public helper functions
public Node getRoot() {
return root;
}
//Exporting a non public Type through public API
///-------------------------------------------Helper Functions
private boolean isLeaf(Node node) {
if (node == null) {
return false;
}
if (node.left == null && node.right == null) {
return true;
}
return false;
}
///-----------------------------------------------------------
private boolean sameTree(Node n1, Node n2) {
if ((n1 == null && n2 == null)) {
return true;
} else {
if ((n1 == null || n2 == null)) {
return false;
} else {
if ((n1.data == n2.data)) {
return (sameTree(n1.left, n2.left) && sameTree(n1.right, n2.right));
}
}
}
return false;
}
private void doubleTree(Node node) {
//create a copy
//bypass the copy to continue looping
if (node == null) {
return;
}
Node copyNode = new Node(node.data);
Node temp = node.left;
node.left = copyNode;
copyNode.left = temp;
doubleTree(copyNode.left);
doubleTree(node.right);
}
private void mirror(Node node) {
if (node == null) {
return;
}
Node temp = node.left;
node.left = node.right;
node.right = temp;
mirror(node.left);
mirror(node.right);
}
private void printPaths(Node node, List pathSoFar) {
if (node == null) {
return;
}
pathSoFar.add(node.data);
if (isLeaf(node)) {
System.out.println("path in tree:" + pathSoFar);
pathSoFar.remove(pathSoFar.lastIndexOf(node.data)); //only the current node, a node.data may be duplicated
return;
} else {
printPaths(node.left, pathSoFar);
printPaths(node.right, pathSoFar);
}
}
private boolean hasPathSum(int pathsum, Node node) {
if (node == null) {
return false;
}
int val = pathsum - node.data;
boolean ret = false;
if (val == 0 && isLeaf(node)) {
ret = true;
} else if (val == 0 && !isLeaf(node)) {
ret = false;
} else if (val != 0 && isLeaf(node)) {
ret = false;
} else if (val != 0 && !isLeaf(node)) {
//recurse further
ret = hasPathSum(val, node.left) || hasPathSum(val, node.right);
}
return ret;
}
private void printPostorder(Node node) { //inorder traversal
if (node == null) {
return;
}
printPostorder(node.left);
printPostorder(node.right);
System.out.print(" " + node.data);
}
private void printTree(Node node) { //inorder traversal
if (node == null) {
return;
}
printTree(node.left);
System.out.print(" " + node.data);
printTree(node.right);
}
private int minValue(Node node) {
if (node == null) {
//error case: this is not supported
return -1;
}
if (node.left == null) {
return node.data;
} else {
return minValue(node.left);
}
}
private int maxValue(Node node) {
if (node == null) {
//error case: this is not supported
return -1;
}
if (node.right == null) {
return node.data;
} else {
return maxValue(node.right);
}
}
private int maxDepth(Node node) {
if (node == null || (node.left == null && node.right == null)) {
return 0;
}
int ldepth = 1 + maxDepth(node.left);
int rdepth = 1 + maxDepth(node.right);
if (ldepth > rdepth) {
return ldepth;
} else {
return rdepth;
}
}
private int size(Node node) {
if (node == null) {
return 0;
}
return 1 + size(node.left) + size(node.right);
}
private Node insert(int data, Node node) {
if (node == null) {
node = new Node(data);
} else if (data <= node.data) {
node.left = insert(data, node.left);
} else {
node.right = insert(data, node.right);
}
//control should never reach here;
return node;
}
private boolean lookup(int data, Node node) {
if (node == null) {
return false;
}
if (node.data == data) {
return true;
}
if (data < node.data) {
return lookup(data, node.left);
} else {
return lookup(data, node.right);
}
}
public static void main(String[] args) {
BinarySearchTree bst = new BinarySearchTree();
int treesize = 5;
bst.buildTree(treesize);
//treesize = bst.buildTreeFromOutputString("4 4 4 6 7");
treesize = bst.buildTreeFromOutputString("3 4 6 3 6");
//treesize = bst.buildTreeFromOutputString("10");
for (int i = 0; i < treesize; i++) {
System.out.println("Searching:" + i + " found:" + bst.lookup(i));
}
System.out.println("tree size:" + bst.size());
System.out.println("maxDepth :" + bst.maxDepth());
System.out.println("minvalue :" + bst.minValue());
System.out.println("maxvalue :" + bst.maxValue());
bst.printTree();
bst.printPostorder();
int pathSum = 10;
System.out.println("hasPathSum " + pathSum + ":" + bst.hasPathSum(pathSum));
pathSum = 6;
System.out.println("hasPathSum " + pathSum + ":" + bst.hasPathSum(pathSum));
pathSum = 19;
System.out.println("hasPathSum " + pathSum + ":" + bst.hasPathSum(pathSum));
bst.printPaths();
bst.printTree();
//bst.mirror();
System.out.println("Tree after mirror function:");
bst.printTree();
//bst.doubleTree();
System.out.println("Tree after double function:");
bst.printTree();
System.out.println("tree size:" + bst.size());
System.out.println("Same tree:" + bst.sameTree(bst));
BinarySearchTree bst2 = new BinarySearchTree();
bst2.buildTree(treesize);
treesize = bst2.buildTreeFromOutputString("3 4 6 3 6");
bst2.printTree();
System.out.println("Same tree:" + bst.sameTree(bst2));
System.out.println("---");
}
}
Now the problem is that netbeans shows Warning: Exporting a non public Type through public API for function getRoot().
I write this function to get root of tree to be used in sameTree() function, to help comparison of "this" with given tree.
Perhaps this is a OOP design issue... How should I restructure the above code that I do not get this warning and what is the concept I am missing here?
The issue here is that some code might call getRoot() but won't be able to use it's return value since you only gave package access to the Node class.
Make Node a top level class with its own file, or at least make it public
I don't really understand why you even created the getRoot() method. As long as you are inside your class you can even access private fields from any other object of the same class.
So you can change
public boolean sameTree(BinarySearchTree bst) { //is this tree same as another given tree?
return sameTree(this.root, bst.getRoot());
}
to
public boolean sameTree(BinarySearchTree bst) { //is this tree same as another given tree?
return sameTree(this.root, bst.root);
}
I would also add a "short path" for the case you pass the same instance to this method:
public boolean sameTree(BinarySearchTree bst) { //is this tree same as another given tree?
if (this == bst) {
return true;
}
return sameTree(this.root, bst.root);
}