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Others/Buzz_number.cpp

@@ -0,0 +1,17 @@
+//A buzz number is a number that is either divisble by 7 or has last digit as 7.
+#include <iostream>
+using namespace std;
+int main()
+{
+  int n,t;
+  cin >> t;
+  while(t--)
+  {
+   cin >> n;
+   if((n%7==0)||(n%10==7))
+    cout << n << " is a buzz number" << endl;
+   else
+    cout << n << " is not a buzz number" << endl;
+  }
+  return 0;
+}

Others/Decimal To Binary.cpp

@@ -0,0 +1,20 @@
+#include<iostream>
+using namespace std;
+int main()
+{
+	int number;
+	cin>>number;
+	int remainder,binary=0,var=1;
+
+do{
+		
+	 remainder=number%2;
+	number=number/2;
+	binary=binary+(remainder*var);
+	var=var*10;
+
+
+}
+while(number>0);
+	cout<<binary;
+}

Others/Decimal To Hexadecimal .cpp

@@ -0,0 +1,51 @@
+#include <iostream>
+
+using namespace std;
+
+void main(void)
+{
+	int valueToConvert = 0; //Holds user input
+	int hexArray[8];       //Contains hex values backwards
+	int i = 0;             //counter
+	int lValue = 0;       //Last Value of Hex result
+
+	cout << "Enter a Decimal Value" << endl; //Displays request to stdout
+	cin >> valueToConvert;					        //Stores value into valueToConvert via user input
+
+	while (valueToConvert > 0)        //Dec to Hex Algorithm
+	{
+		lValue = valueToConvert % 16;        //Gets remainder
+		valueToConvert = valueToConvert / 16;
+		hexArray[i] = lValue;             //Stores converted values into an array
+		i++;
+	}
+	cout << "Hex Value: ";
+	while (i > 0)
+	{
+		//Displays Hex Letters to stdout
+		switch (hexArray[i - 1]) {
+			case 10:
+				cout << "A"; 
+				break;
+			case 11:
+				cout << "B";
+				break;
+			case 12:
+				cout << "C";
+				break;
+			case 13:
+				cout << "D";
+				break;
+			case 14: 
+				cout << "E";
+				break;
+			case 15:
+				cout << "F";
+				break;
+			default:
+				cout << hexArray[i - 1]; //if not an int 10 - 15, displays int value
+		}
+			i--;
+	}
+	cout << endl;
+}

Others/GCD_of_n_numbers.cpp

@@ -0,0 +1,23 @@
+//This program aims at calculating the GCD of n numbers by division method
+#include <iostream>
+using namepsace std;
+int main()
+{
+  cout <<"Enter value of n:"<<endl;
+  cin >> n;
+  int a[n];
+  int i,j,gcd;
+  cout << "Enter the n numbers:" << endl;
+  for(i=0;i<n;i++)
+    cin >> a[i];
+  j=1; //to access all elements of the array starting from 1
+  gcd=a[0];
+  while(j<n)
+  {
+    if(a[j]%gcd==0) //value of gcd is as needed so far
+     j++;          //so we check for next element
+    else
+     gcd=a[j]%gcd; //calculating GCD by division method
+  }
+  cout << "GCD of entered n numbers:" << gcd;
+}

Others/Happy_number.cpp

@@ -0,0 +1,26 @@
+/* A happy number is a number whose sum of digits is calculated until the sum is a single digit,
+  and this sum turns out to be 1 */
+#include <iostream>
+using namespace std;
+int main()
+{
+  int n,k,s=0,d;
+  cout << "Enter a number:";
+  cin >> n;
+  s=0;k=n;
+  while(k>9)
+  {
+    while(k!=0)
+    {
+      d=k%10;
+      s+=d;
+      k/=10;
+    }
+    k=s;
+    s=0;
+  }
+  if(k==1)
+   cout << n << " is a happy number" << endl;
+  else
+   cout << n << " is not a happy number" << endl;
+}

Others/Paranthesis Matching.cpp

@@ -0,0 +1,65 @@
+#include<iostream>
+#include<stdlib.h>
+#include<string.h>
+#include<stdio.h>
+using namespace std;
+
+char stack[100];
+int top=0;
+
+void push(char ch)
+{
+	stack[top++]=ch;
+}
+
+char pop()
+{
+	return stack[--top];
+}
+
+bool check(char x, char y)
+{
+	if ((x=='(' && y==')') || (x=='{' && y=='}') || (x=='[' && y==']') || (x=='<' && y=='>'))
+	{
+		return true;
+	}
+	else
+	{
+		return false;
+	}
+}
+
+
+
+int main()
+{
+	char exp[100];
+	cout<<"Enter The Expression : ";
+	gets(exp);
+	for (int i = 0; i < strlen(exp); i++)
+	{
+			if (exp[i]=='(' || exp[i]=='{' || exp[i]=='[' || exp[i]=='<')
+			{
+				push(exp[i]);
+			}
+			else if (exp[i]==')' || exp[i]=='}' || exp[i]==']' || exp[i]=='>')
+			{
+				if(!check(pop(), exp[i]))
+				{
+					cout<<"\nWrong Expression";
+					exit(0);
+				}
+			}
+	}
+
+	if(top==0)
+	{
+		cout<<"Correct Expression";
+	}
+	else
+	{
+		cout<<"\nWrong Expression";
+	}
+	
+	return 0;
+}

Others/Sparse matrix.cpp

@@ -0,0 +1,28 @@
+/*A sparse matrix is a matrix which has number of zeroes greater than (m*n)/2,
+where m and n are the dimensions of the matrix.*/
+#include <iostream>
+int main()
+{
+  int m,n,i,j,c=0;
+  cout << "Enter dimensions of matrix:";
+  cin >> m >> n;
+  int a[m][n];
+  cout << "Enter matrix elements:";
+  for(i=0;<m;i++)
+  {
+    for(j=0;j<n;j++)
+     cin >> a[i][j];
+  }
+  for(i=0;i<m;i++)
+  {
+    for(j=0;j<n;j++)
+    {
+      if(a[i][j]==0)
+       c++; //Counting number of zeroes
+    }
+  }
+  if(c>((m*n)/2)) //Checking for sparse matrix
+   cout << "Sparse matrix";
+  else
+   cout << "Not a sparse matrix";
+}

Others/Strassen Matrix Multiplication.cpp

@@ -0,0 +1,60 @@
+#include <iostream>
+using namespace std;
+
+Multiply(int A[][], int B[][], int n)
+{
+	if (n==2)
+	{
+		int p1= (a[0][0] + a[1][1])*(b[0][0]+b[1][1]);
+	  	int p2= (a[1][0]+a[1][1])*b[0][0];
+	 	int p3= a[0][0]*(b[0][1]-b[1][1]);
+	 	int p4= a[1][1]*(b[1][0]-b[0][0]);
+	 	int p5= (a[0][0]+a[0][1])*b[1][1];
+	 	int p6= (a[1][0]-a[0][0])*(b[0][0]+b[0][1]);
+	 	int p7= (a[0][1]-a[1][1])*(b[1][0]+b[1][1]);
+
+
+	 	int c[n][n];
+		c[0][0]=p1+p4-p5+p7;
+ 		c[0][1]=p3+p5;
+ 		c[1][0]=p2+p4;
+ 		c[1][1]=p1-p2+p3+p6;
+
+ 	 	return c[][];
+	}
+	else
+	{
+		
+	}
+
+}
+
+int main()
+{
+	int p,q,r,s;
+	cout<<"Enter the dimensions of Matrices";
+	cin>>n;
+	int A[n][n],;
+	int B[n][n],;
+	cout<<"Enter the elements of Matrix A";
+	for (int i = 0; i < n; i++)
+	{
+		for (int j = 0; j <n ; j++)
+		{
+			cin>>A[i][j];
+		}
+	}
+
+
+	cout<<"Enter the elements of Matrix B";
+	for (int i = 0; i < n; i++)
+	{
+		for (int j = 0; j <n ; j++)
+		{
+			cin>>B[i][j];
+		}
+	}
+
+	Multiply(A, B, n);
+	return 0;
+}

Others/Tower of Hanoi.cpp

@@ -0,0 +1,88 @@
+#include<iostream>
+using namespace std;
+
+struct tower
+{
+	int values[10];
+	int top;
+}F, U, T;
+
+
+
+void show()
+{
+	cout<<"\n\n\tF : ";
+	for(int i=0; i<F.top; i++)
+	{
+		cout<<F.values[i]<<"\t";
+	}
+	cout<<"\n\tU : ";
+	for(int i=0; i<U.top; i++)
+	{
+		cout<<U.values[i]<<"\t";
+	}
+	cout<<"\n\tT : ";
+	for(int i=0; i<T.top; i++)
+	{
+		cout<<T.values[i]<<"\t";
+	}
+}
+
+
+void mov(tower &From, tower &To)
+{
+	--From.top;
+	To.values[To.top]=From.values[From.top];
+	++To.top;
+}
+
+void TH(int n, tower &From, tower &Using, tower &To)
+{
+	
+	if (n==1)
+	{
+		mov(From, To);
+		show();
+		
+	}
+	else
+	{
+		TH(n-1, From, To, Using);
+		mov(From, To);
+		show();
+		TH(n-1, Using, From, To);
+	}
+}
+
+
+
+
+int main()
+{
+	F.top=0;
+	U.top=0;
+	T.top=0;
+
+	int no;
+
+	cout << "\nEnter number of discs : " ;
+	cin >> no;
+	
+	for (int i = no; i >0; i--)
+	{
+		F.values[F.top++]=i;
+	};
+
+	
+
+	
+	
+	show();
+	TH(no, F, U, T);
+	
+
+	
+
+	
+	return 0;
+}

Others/fibonacci.cpp

@@ -0,0 +1,100 @@
+#include <iostream>
+using namespace std;
+
+
+/*
+	Efficient method for finding nth term in a fibonacci number sequence.
+	Uses Dvide and conquer approach
+	Enter Values from 1
+	Eg-
+	1st term = 0;
+	2nd term = 1;
+	3rd term = 1;
+	.
+	.
+	.
+	.
+*/
+int a[2][2] = {{1,1},{1,0}};//fibonacci matrix
+int ans[2][2] = {{1,1},{1,0}};//final ans matrix
+/*
+	Working Principal:
+
+	[F(k+1)	  F(k)]   [1  1]^k
+	|             | = |    |
+	[F(k)	F(k-1)]   [1  0]
+
+	where F(k) is the kth term of the Fibonacci Sequence. 
+
+
+*/
+
+void product(int b[][2],int k[][2])
+{
+	/*
+		Function for computing product of the two matrices b and k
+		and storing them into the variable ans.
+
+		Implementation :
+		Simple matrix multiplication of two (2X2) matrices.
+	*/
+	int c[2][2];//temporary stores the answer
+	c[0][0] = b[0][0]*k[0][0]+b[0][1]*k[1][0];
+	c[0][1] = b[0][0]*k[0][1]+b[0][1]*k[1][1];
+	c[1][0] = b[1][0]*k[0][0]+b[1][1]*k[1][0];
+	c[1][1] = b[1][0]*k[0][1]+b[1][1]*k[1][1];
+	ans[0][0] = c[0][0];
+	ans[0][1] = c[0][1];
+	ans[1][0] = c[1][0];
+	ans[1][1] = c[1][1];
+	
+} 
+
+void power_rec(int n)
+{	
+
+	/*
+		Function for calculating A^n(exponent) in a recursive fashion
+
+		Implementation:
+		A^n = { A^(n/2)*A^(n/2) 			if n is even
+			  { A^((n-1)/2)*A^((n-1)/2)*A   if n is odd
+	*/
+	if((n == 1)||(n==0))
+		return;
+	else
+	{
+		if((n%2) == 0)
+		{	
+			power_rec(n/2);
+			product(ans,ans);
+			
+		}	
+		else
+		{
+			power_rec((n-1)/2);	
+			product(ans,ans);
+			product(ans,a);
+			
+		}
+	}
+}
+
+int main()
+{
+	//Main Function
+	cout <<"Enter the value of n\n";
+	int n;
+	cin >>n;
+	if(n == 1)
+	{
+		cout<<"Ans: 0"<<endl;
+	}
+	else
+	{	
+		power_rec(n-1);
+		cout <<"Ans :"<<ans[0][1]<<endl;
+	}
+	return 0;
+}
+

Others/sieve_of_Eratosthenes.cpp

@@ -0,0 +1,60 @@
+/*
+ * Sieve of Eratosthenes is an algorithm to find the primes 
+ * that is between 2 to N (as defined in main).
+ *
+ * Time Complexity  : O(N)
+ * Space Complexity : O(N)
+ */
+
+#include <iostream>
+using namespace std;
+
+#define MAX 10000000
+
+int primes[MAX];
+
+
+/*
+ * This is the function that finds the primes and eliminates 
+ * the multiples.
+ */
+void sieve(int N)
+{
+  primes[0] = 1;
+  primes[1] = 1;
+  for(int i=2;i<=N;i++)
+    {
+      if(primes[i] == 1) continue;
+      for(int j=i+i;j<=N;j+=i)
+	primes[j] = 1;
+    }
+}
+
+/*
+ * This function prints out the primes to STDOUT
+ */
+void print(int N)
+{
+  for(int i=0;i<=N;i++)
+    if(primes[i] == 0)
+      cout << i << ' ';
+  cout << '\n';
+}
+
+/*
+ * NOTE: This function is important for the 
+ * initialization of the array.
+ */
+void init()
+{
+  for(int i=0;i<MAX;i++)
+    primes[i] = 0;
+}
+
+int main()
+{
+  int N = 100;
+  init();
+  sieve(N);
+  print(N);
+}