From b154f5e6167fe2aff0f8ea99ee49ee816c1d2581 Mon Sep 17 00:00:00 2001
From: Aparna Juhi <54853999+AparnaJuhi@users.noreply.github.com>
Date: Thu, 1 Oct 2020 17:52:06 +0530
Subject: [PATCH] Added some cp solutions

Modular Exponentiation problem was asked in Google and 'Last Digit of Nth Fibonacci' problem was asked in MAQ Software and the 'Paranthesis Checker' is a famous problem of Stacks
---
 divide and conquer/Modular Exponentation.cpp  | 23 ++++++
 .../LastDigit of Nth Fibonacci.cpp            | 49 ++++++++++++
 stack/paranthesisChecker.cpp                  | 74 +++++++++++++++++++
 3 files changed, 146 insertions(+)
 create mode 100644 divide and conquer/Modular Exponentation.cpp
 create mode 100644 dynamic programming/LastDigit of Nth Fibonacci.cpp
 create mode 100644 stack/paranthesisChecker.cpp

diff --git a/divide and conquer/Modular Exponentation.cpp b/divide and conquer/Modular Exponentation.cpp
new file mode 100644
index 0000000..990c47b
--- /dev/null
+++ b/divide and conquer/Modular Exponentation.cpp	
@@ -0,0 +1,23 @@
+#include<bits/stdc++.h>
+using namespace std;
+int main() {
+	long long int t;cin>>t;
+	while(t--)
+	{
+	    long long int x,y,p,res=1;
+		cin>>x>>y>>p;
+	    if(x==0)
+	    cout<<"0\n";
+	    else
+	    {
+	        while(y)
+	        {
+	            if(y%2!=0)
+	            res=(res*x)%p;
+	            y=y/2;
+	            x=(x*x)%p;
+	        }
+	        cout<<res<<"\n";
+	    }
+	}
+}
diff --git a/dynamic programming/LastDigit of Nth Fibonacci.cpp b/dynamic programming/LastDigit of Nth Fibonacci.cpp
new file mode 100644
index 0000000..738ca84
--- /dev/null
+++ b/dynamic programming/LastDigit of Nth Fibonacci.cpp	
@@ -0,0 +1,49 @@
+
+/*  Program to print last digit of nth fibonacci
+Input:
+N = 14
+Output:
+7
+Explanation:
+14th Fibonacci number is 377
+It's last digit is 7
+
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+
+class Solution{
+public:
+    int fib(int n){
+        if(n==0)
+        return 0;
+        else if(n==1 || n==2)
+        return 1;
+        else
+        {
+            int a[n];
+            a[0]=1;
+            a[1]=1;
+            for(int i=2;i<n;i++)
+            a[i]=(a[i-1]+a[i-2])%10;
+            return a[n-1];
+        }
+        
+    }
+};
+
+
+int main() 
+{ 
+    int t;
+    cin>>t;
+    while(t--)
+    {
+        int N;
+        cin>>N;
+        Solution ob;
+        cout << ob.fib(N) << endl;
+    }
+    return 0; 
+} 
diff --git a/stack/paranthesisChecker.cpp b/stack/paranthesisChecker.cpp
new file mode 100644
index 0000000..7726472
--- /dev/null
+++ b/stack/paranthesisChecker.cpp
@@ -0,0 +1,74 @@
+/* The famous problem of checking Paranthesis is 'Balanced' or 'Not Balanced' using stacks. 
+For example, the program should print 'balanced' for exp = “[()]{}{[()()]()}” 
+and 'not balanced' for exp = “[(])”
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+int main() {
+	int t;cin>>t;
+	while(t--)
+	{
+	    string n;
+		cin>>n;
+	    stack<int>s;
+		int flag=0;
+	    for(int i=0;i<n.length();i++)
+	    {
+	    	/* While traversing the string if found symbols like '(', '{' and '[' push them in stack*/
+	        if(n[i]=='(' || n[i]=='{' || n[i]=='[')
+	        s.push(n[i]);
+	        else
+	        { 
+	        /* If string starts with ')', '}, or ']', then the string can never be balances, so raise the flag*/
+			if(s.empty())
+	        {
+	            flag=1;
+	            break;
+	        }
+	        else if(n[i]==')')
+	        {
+	        	/* If string starts with ')' then the top of the stack must contain '(' for the string to be valid.
+				Pop the top of stack.
+				*/
+	            int t=s.top();
+	            s.pop();
+	            if(t!='(')
+	            {
+	                flag=1;break;
+	            }
+	        }   
+	        else if(n[i]=='}')
+	        {
+	        		/* If string starts with '}' then the top of the stack must contain '(' for the string to be valid.
+				Pop the top of stack.
+				*/
+	            int t=s.top();
+	            s.pop();
+	            if(t!='{')
+	            {
+	                flag=1;break;
+	            }
+	        }
+	         else if(n[i]==']')
+	        {
+	        		/* If string starts with ']' then the top of the stack must contain '(' for the string to be valid.
+				Pop the top of stack.
+				*/
+	            int t=s.top();
+	            s.pop();
+	            if(t!='[')
+	            {
+	                flag=1;break;
+	            }
+	        }
+	        }
+	    }
+	    	/* If at last the stack is empty and the flag value is also 1, then it is balanced else unbalanced.
+				*/
+	    if(flag==0 && s.empty())
+	    cout<<"balanced\n";
+	    else
+	    cout<<"not balanced\n";
+	}
+}