Adding-Algorithms

data-structures/UseStack.java

@@ -0,0 +1,38 @@
+class Stack
+{
+	int stcksize=100;
+	int stck[] = new int[stcksize];
+	int tos;
+	Stack() 
+	{
+		tos=-1;
+	}
+	void push(int item) 
+	{
+		if(tos==stcksize-1)
+			System.out.println("Stack Overflow");
+		else
+			stck[++tos]=item;
+	}
+	int pop()
+	{
+		if(tos<0)
+		{
+			System.out.println("Stack Underflow.");
+			return 0;
+		}
+		else
+			return stck[tos--];
+	}
+}
+public class UseStack
+{
+	public static void main(String args[])
+	{
+		Stack s=new Stack();
+		s.push(1);
+		s.push(2);
+		s.push(3);
+		s.pop(); // return 3 as it was the last inserted element
+	}
+}

dynamic-programming/LongestCommonSubsequence.java

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+// Finding Longest Common Subsequence of Two Strings Using Dynamic Programming
+import java.util.Scanner;
+public class LongestCommonSubsequence
+{
+	int lcs(char[] X, char[] Y, int m, int n) 
+	{
+		int DP[][] = new int[m+1][n+1];
+		// Bottom-Up Approach for dp 
+		for(int i=0;i<=m;i++) 
+		{
+			for(int j=0;j<=n;j++)
+			{
+				if(i==0 || j==0)
+					DP[i][j]=0; 
+				else if(X[i-1]==Y[j-1]) 
+					DP[i][j]=DP[i-1][j-1]+1; 
+			        else
+					DP[i][j] = max(DP[i-1][j], DP[i][j-1]); 
+			}
+		}
+		return DP[m][n]; 
+	}
+	int max(int a, int b) 
+	{
+		if(a>b)
+			return a;
+		else
+			return b;
+	} 
+	public static void main(String[] args)
+	{ 
+		LongestCommonSubsequence obj=new LongestCommonSubsequence();
+		String s1="",s2="";
+		Scanner scan=new Scanner(System.in);
+		System.out.println("Enter 1st String");
+		s1=scan.next();
+		System.out.println("Enter 2nd String");
+		s2=scan.next();
+	  	char[] X=s1.toCharArray(); 
+		char[] Y=s2.toCharArray(); 
+		int m=X.length; 
+		int n=Y.length; 
+	  	System.out.println("Length of Longest Common Subsequence is: "+obj.lcs(X,Y,m,n)); 
+	}  
+}