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Stack/InfixEvaluator.java

@@ -0,0 +1,66 @@
+import java.util.Scanner;
+class InfixEvaluator
+{
+	static int pow(int a,int b)
+	{
+		int r=1;
+		for(int j=0;j<b;j++)
+		{
+			r=r*a;
+		}
+		return r;
+	}
+	public static void main(String[] args)
+	{
+		Scanner in = new Scanner(System.in);
+		System.out.println("Enter Post Form:");
+		String y =in.nextLine();
+		int n = y.length();
+		StackInt s=new StackInt(n);
+		for(int i= 0;i<n;i++)
+		{
+			char x = y.charAt(i);
+			if((x=='+') || (x=='-') || (x=='*') || (x=='/') || (x=='^'))
+			{
+				if(s.getTop()==-1)
+					System.out.println("Stack is Empty");
+				else
+				{
+					int b=s.pop();
+					int a=s.pop();
+					switch(x)
+					{
+						case '+': 
+							s.push(a+b);
+							break;
+						case '-':
+							s.push(a-b);
+							break;
+						case '*':
+							s.push(a*b);
+							break;
+						case '/':
+							s.push(a/b);
+							break;
+						case '^':
+							s.push(pow(a,b));
+							break;
+						default:
+							System.out.println("Invalid Character");
+							break;
+ 					}
+				}
+			}
+			else if(x==' ')
+			{
+				int o=0;
+			}
+			else
+			{
+				s.push(Integer.parseInt(String.valueOf(x)));
+				System.out.println(Integer.parseInt(String.valueOf(x)));
+			}
+		}
+		System.out.println("Evaluation Value"+s.peek());
+	}
+}

Stack/Paranthesis.java

@@ -0,0 +1,58 @@
+import java.util.Scanner;
+class Paranthesis
+{
+	public static void main(String[] args)
+	{
+		Scanner in = new Scanner(System.in);
+		String a = in.next();
+		int n = a.length();
+		StackChar s = new StackChar(n);
+		int flag=1;
+		for(int i= 0;i<n;i++)
+		{
+			char x = a.charAt(i);
+			if((x=='(') || (x=='{') || (x=='['))
+				s.push(x);
+			else if(x==')')
+			{
+				if(s.peek()=='(')
+					s.pop();
+				else
+				{
+					flag=0;
+					break;
+				}
+			}
+			else if(x=='}')
+			{
+				if(s.peek()=='{')
+					s.pop();
+				else
+				{
+					flag=0;
+					break;
+				}
+			}
+			else if(x==']')
+			{
+				if(s.peek()=='[')
+					s.pop();
+				else
+				{
+					flag=0;
+					break;
+				}
+			}
+		}
+		if(flag==0)
+			System.out.println("Not Balanced");
+		if(flag==1)
+		{
+			if(s.getTop()== -1)
+				System.out.println("Balanced");
+			else
+				System.out.println("Not Balanced");
+		}
+
+	}
+}

Stack/PostFix.java

@@ -0,0 +1,66 @@
+import java.util.Scanner;
+class PostFix
+{
+	public static void main(String args[])
+	{
+		Scanner in = new Scanner(System.in); 
+		String a = in.next();
+		int n = a.length();
+		char[] b=new char[a.length()];
+		int j=0;
+		StackChar s = new StackChar(n);
+		for(int i= 0;i<n;i++)
+		{
+			char x = a.charAt(i);
+			if(x=='(')
+				s.push(x);
+			else if((x=='+') || (x=='-') || (x=='*') || (x=='/') || (x=='^'))
+			{
+				if(s.getTop()== -1)
+					s.push(x);
+				else
+				{
+					char k = s.peek();
+					if(s.prec(x)>s.prec(k))
+						s.push(x);
+					else
+					{
+						while(s.prec(x)<=s.prec(k))
+						{
+							b[j]=s.pop();
+							j++;
+							k=s.peek();
+						}
+						s.push(x);
+					}
+				}
+
+			}
+			else if(x==')')
+			{
+				while(s.peek()!='(')
+				{
+					b[j]=s.pop();
+					j++;
+				}
+				s.pop();
+
+			}
+			else
+			{
+				b[j]=x;
+				j++;
+			}
+		}
+		while(s.getTop()!= -1)
+		{
+			b[j]=s.pop();
+			j++;
+		}
+		for(int i=0;i<n;i++)
+		{
+			System.out.print(b[i]);
+		}
+
+	}
+}

Stack/StackChar.java

@@ -0,0 +1,67 @@
+
+
+import java.util.Scanner;
+
+public class StackChar 
+{
+	public int top;
+	Scanner in = new Scanner(System.in);
+	char[] a= new char[12];
+	StackChar(int sz)
+	{
+		top=-1;
+		a = new char[sz];
+
+	}
+	public void push(char x)
+	{
+		if(top>=(a.length-1))
+			System.out.println("Stack is Full");
+		else
+		{
+			top++;
+			a[top]=x;
+		}
+	}
+	public char pop()
+	{
+		if(top==(-1))
+		{
+			return 0;
+		}
+		else
+		{
+			return a[top--];
+		}
+	}
+	public int getTop()
+	{
+		return top;
+	}
+	public char peek()
+	{
+		if(top==-1)
+		{
+			return 0;
+		}
+		else
+			return a[top];
+	}
+	public int prec(char x)
+	{
+		if(x=='+')
+			return 1;
+		else if(x=='-')
+			return 1;
+		else if(x=='*')
+			return 2;
+		else if(x=='/')
+			return 2;
+		else if(x=='^')
+			return 3;
+		else
+			return 0;
+
+	}
+
+}

Stack/StackInt.java

@@ -0,0 +1,117 @@
+
+
+import java.util.Scanner;
+public class StackInt
+{
+	private int[] arr = new int[5];
+	private int top=-1; 
+	Scanner in = new Scanner(System.in);
+	public StackInt()
+	{
+		arr =new int[10];
+		top = -1;
+	}
+	public StackInt(int sz)
+	{
+		arr = new int[sz];
+		top= -1;
+	}
+	public int getTop()
+	{
+		return top;
+	}
+	public int[] getArr()
+	{
+		return arr;
+	}
+	public void readArr(int n)
+	{
+		for(int i=0;i<n;i++)
+		{
+			arr[i]=in.nextInt();
+			top++;
+		}
+	}
+	public void printArr()
+	{
+		for(int i=0;i<=top;i++)
+		{
+			System.out.print(arr[i]+"		");
+		}
+		System.out.println();
+	}
+	public void push(int x)
+	{
+		if(top>=(arr.length-1))
+			System.out.println("Stack is Full");
+		else
+		{
+			top++;
+			arr[top]=x;
+		}
+	}
+	public int pop()
+	{
+		if(top==(-1))
+		{
+			System.out.println("Can't pop. Stack is empty");
+			return 0;
+		}
+		else
+		{
+			return arr[top--];
+		}
+	}
+	public int peek()
+	{
+		if(top==-1)
+		{
+			System.out.println("Can't peek");
+			return 0;
+		}
+		else
+			return arr[top];
+	}
+	public boolean equals(StackInt a)
+	{
+		int flag=1;
+		if(this.top==a.top)
+		{
+			for(int i=0;i<=top;i++)
+			{
+				if(this.arr[i]!=a.arr[i])
+					flag=0;
+
+			}
+			if(flag==0)
+				return false;
+			else
+			{
+				return true;
+			}
+		}
+		else
+			return false;
+	}
+	public int getm()
+	{
+		int m=arr[0];
+		for(int i=0;i<=top;i++)
+		{
+			if(arr[i]<m)
+				m=arr[i];
+		}
+		return m;
+	}
+	public StackInt copy()
+	{
+		StackInt a= new StackInt();
+		a.top=this.top;
+		for(int i=0;i<=top;i++)
+		{
+			a.arr[i]=this.arr[i];
+		}
+		return a;
+	}
+
+}