2. Write a C program to swap two variables without using a temporary variable?

Using pointer you can directly change the variable without using any extra variable.
bool Swap(int *ptrVal1, int *ptrVal2)
{
if(ptrVal1 == NULL || ptrVal2 == NULL)
return false;
*ptrVal1 = *ptrVal1 + *ptrVal2;
*ptrVal2 = *ptrVal1 - *ptrVal2;
*ptrVal1 = *ptrVal1 - *ptrVal2;
return true;
}

Trie data structure sample in cpp

//trie.h
#pragma once

#define ALPHABET_SIZE 26
struct Trie_Node
{
int value;
Trie_Node * childs[ALPHABET_SIZE];
};

class Trie
{
private:
Trie_Node *root;
int count;
Trie_Node* CreateNode();
public:
Trie(void);
~Trie(void);
int Search(const char key[]);
void Insert(const char key[]);
};

//trie.cpp
#include "stdafx.h"
#include "Trie.h"
#include
#include

#define CHARTOINDEX(c) ((int)c - (int)'a')
using namespace std;

Trie::Trie(void)
{
this->root = CreateNode();
this->count = 0;
}


Trie::~Trie(void)
{
}

Trie_Node* Trie::CreateNode()
{
Trie_Node* newnode = new Trie_Node();
if(newnode)
{
newnode->value = 0;
for(int i = 0; i < ALPHABET_SIZE; i++) newnode->childs[i] = nullptr;
}

return newnode;
}

void Trie::Insert(const char key[])
{
std::locale loc;
int length = strlen(key);
int index = 0;
char lower;
this->count++;
Trie_Node* pCrawl = this->root;
for(int level = 0; level < length; level++) { lower = std::islower(key[level], loc) ? key[level] : _tolower(key[level]); index = CHARTOINDEX(lower); //filtering any non alphabetic character. if( index < 0 || index > 26)
continue;
if(!pCrawl->childs[index])
{
pCrawl->childs[index] = CreateNode();
}
pCrawl = pCrawl->childs[index];
}

//mark last node as leaf by assigning value
pCrawl->value = this->count;
}

int Trie::Search(const char key[])
{
std::locale loc;
int length = strlen(key);
int index = 0;
char lower ;
Trie_Node* pCrawl = this->root;
for(int level = 0; level < length; level++) { lower = std::islower(key[level], loc) ? key[level] : _tolower(key[level]); index = CHARTOINDEX(lower); //filtering any non alphabetic character. if( index < 0 || index > 26)
return 0;
if(!pCrawl->childs[index])
return 0;

pCrawl = pCrawl->childs[index];

}
return (nullptr != pCrawl && pCrawl->value);
}

//main.cpp
#include "Trie.h"
#include
#include
#include
#include
#include

using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
char output[][32] = {"not present in trie", "present in trie"};
Trie* mytrie = new Trie();
string temp;
while(1)
{
cout << "Enter the word or sentence in the trie.....'0' to exit " << endl; getline(cin, temp); if(temp.length() == 1) { if( '0' == temp[0]) break; } istringstream iss(temp); vector tokens;
copy(istream_iterator(iss),
istream_iterator(),
back_inserter(tokens));

for(auto word : tokens)
mytrie->Insert(word.c_str());
}

while(1)
{
cout << "Enter the word to search in the trie.....'0' to exit " << endl; getline(cin, temp); if(temp.length() == 1) { if( '0' == temp[0]) break; } cout << "searching '" << temp.c_str() <<"' --------" << output[mytrie->Search(temp.c_str())] << endl; } getchar(); return 0; }