Srilekha_Week2_codes_outputs

Week1/Srilekha_Vinjamara/10_cpp.cpp

@@ -0,0 +1,29 @@
+/* 
+c++ program to find GCD of two numbers
+Approach: find maximum of the given 2 numbers and find a number in the range 1 to this maximum which will be the GCD
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+	#ifndef ONLINE_JUDGE
+	freopen("input.txt", "r", stdin);
+	freopen("output.txt", "w", stdout);
+	#endif
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	// num1 = user input1, num2 = user input2
+	int num1, num2;
+	cin >> num1 >> num2;
+	int maxi = (num1 > num2) ? num1 : num2;
+	for(int i = maxi; i >= 1; i--){
+		if(num1 % i == 0 && num2 % i == 0){
+			cout << "GCD of " << num1 << " & " << num2 << " is: " << i;
+			break;
+		}
+	}
+	return 0;
+}

Week1/Srilekha_Vinjamara/11_cpp .cpp

@@ -0,0 +1,38 @@
+/* 
+c++ program to find all prime numbers till and including given input number
+Approach: sieve of erasthosthenes, all multiples of a number will not be prime and are marked false
+*/
+
+#include <vector>
+#include <iostream>
+using namespace std;
+
+// function isPrime is used to find if all prime numbers from 2 to the given range = num
+void isPrime(int num){
+    // vec is the variable used to store all prime numbers till a number num
+    vector<bool> vec(num, true);
+
+    for(int i = 2; (i*i) < num; i++){
+        if(vec[i] == true){
+            for(int j = (i*i); j <= num; j += i)
+                vec[j] = false;
+        }
+    }
+    for(int i = 2; i <= vec.size(); i++){
+        if(vec[i])
+            cout << i << " ";
+    }
+}
+
+int main() {
+	//code
+	int t;
+	cin >> t;
+	while(t--){
+	    int num;
+	    cin >> num;
+	    isPrime(num);
+	    cout << "\n";
+	}
+	return 0;
+}

Week1/Srilekha_Vinjamara/12_cpp.cpp

@@ -0,0 +1,38 @@
+/* 
+c++ program to find all prime numbers till and NOT including given input number
+Approach: sieve of erasthosthenes, all multiples of a number will not be prime and are marked false
+*/
+
+#include <vector>
+#include <iostream>
+using namespace std;
+
+// function isPrime is used to find if all prime numbers from 2 to the given range = num
+void isPrime(int num){
+    // vec is the variable used to store all prime numbers till and NOT including number num
+    vector<bool> vec(num, true);
+
+    for(int i = 2; (i*i) < num; i++){
+        if(vec[i] == true){
+            for(int j = (i*i); j <= num; j += i)
+                vec[j] = false;
+        }
+    }
+    for(int i = 2; i <= vec.size(); i++){
+        if(vec[i])
+            cout << i << " ";
+    }
+}
+
+int main() {
+	//code
+	int t;
+	cin >> t;
+	while(t--){
+	    int num;
+	    cin >> num;
+	    isPrime(num);
+	    cout << "\n";
+	}
+	return 0;
+}

Week1/Srilekha_Vinjamara/13_cpp.cpp

@@ -0,0 +1,40 @@
+/* 
+c++ program to find a number raised to it's power
+Approach: modular exponentiation/fast multiplication of a number with it's power
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+// function modExp is used to find modular exponentiation/fast multiplication of a number x to it's power y
+long long modExp(long long x, long long y, long long p){
+	// ans = modular exponentiation final value i.e. result
+	long long ans = 1;
+
+	x = x % p;
+	if(x == 0)
+		return 0;
+	while(y > 0){
+		if(y & 1)
+			ans = (ans*x) % p;
+		x = (x*x) % p;
+		y = y >> 1;
+	}
+	return ans;
+}
+
+int main()
+{
+	#ifndef ONLINE_JUDGE
+	freopen("input.txt", "r", stdin);
+	freopen("output.txt", "w", stdout);
+	#endif
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	// x = base, y = power, p = modulus value
+	long long x, y, p;
+	cin >> x >> y >> p;
+	cout << modExp(x, y, p);
+	return 0;
+}

Week1/Srilekha_Vinjamara/14_cpp.cpp

@@ -0,0 +1,30 @@
+/* 
+c++ program to find a prime number
+Approach: if number is divisible by any number other than 1 and itself, flag and mark as prime (till range as square root of input)
+*/
+
+#include <iostream>
+using namespace std;
+
+int main() {
+	//code
+
+	// t = number of test cases
+	int t;
+	cin >> t;
+	while(t--){
+	    long int num, flag = 0;
+    	cin >> num;
+    	for(int i = 2; (i*i) <= num; i++){
+    	    if(num % i == 0){
+    	        flag = 1;
+    	        break;
+    	    }
+    	}
+    	if(flag == 0)
+    	    cout << "Yes\n";
+    	else
+    	    cout << "No\n";
+	}
+	return 0;
+}

Week1/Srilekha_Vinjamara/15_cpp.cpp

@@ -0,0 +1,50 @@
+/* 
+c++ program to find pairs of primes whose product is less than or equal to the given input value
+Approach: find all prime numbers, store them in a vector and then for every possible subset pair, if their product <= given input, print the pair
+*/
+
+#include <vector>
+#include <iostream>
+using namespace std;
+
+// function isPrime is used to find if a number n is prime or not
+bool isPrime(long int n)
+{
+    int flag=0;
+    for(int i=2;(i*i)<=n;i++){
+        if(n%i==0){
+            flag=1;
+            break;
+        }
+    }
+    if(flag==0) 
+        return true;
+    else 
+        return false;
+}
+
+int main() {
+	//code
+	int t;
+	cin >> t;
+	while(t--){
+	    // vec is a vector used to stor all prime numbers till given input range number: num
+	    vector<int> vec;
+
+	    long long num;
+	    cin >> num;
+	    for(int i = 2; i <= num; i++){
+	        if(isPrime(i))
+	            vec.push_back(i);
+	    }
+	    for(int i = 0; i < vec.size(); i++){
+	        for(int j = 0; j < vec.size(); j++){
+	            if(vec[i] * vec[j] <= num)
+	                cout << vec[i] << " " 
+	                     << vec[j] << " ";
+	        }
+	    }
+	    cout << "\n";
+	}
+	return 0;
+}

Week1/Srilekha_Vinjamara/16_cpp.cpp

@@ -0,0 +1,26 @@
+/* 
+c++ program to find if a number is a power of 2
+Approach: using bitwise operations gives smallest worst case time complexity, power of 2 iff the bitwise and(&) of input number num and (num - 1) equal 0. In all other cases, the input number num isn't a power of 2 
+*/
+
+#include <iostream>
+using namespace std;
+
+int main() {
+	//code
+	long long t;
+	cin >> t;
+	while(t--){
+	    // num = user input number
+	    long long num;
+
+	    cin >> num;
+	    if(num == 0)
+	        cout << "NO\n";
+	    else if((num & (num - 1)) == 0)
+	        cout << "YES\n";
+	    else
+	        cout << "NO\n";
+	    else if((num & (num - 1)) == 0)
+	return 0;
+}

Week1/Srilekha_Vinjamara/1_cpp.cpp

@@ -0,0 +1,22 @@
+/* 
+c++ program to print square of a number 
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+	#ifndef ONLINE_JUDGE
+	freopen("input.txt", "r", stdin);
+	freopen("output.txt", "w", stdout);
+	#endif
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	// num is a variable used to take input 
+	float num; 
+	cin >> num;
+	cout << num*num;
+	return 0;
+}

Week1/Srilekha_Vinjamara/2_cpp.cpp

@@ -0,0 +1,24 @@
+/* 
+c++ program to print multiplication table of a number 
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+	#ifndef ONLINE_JUDGE
+	freopen("input.txt", "r", stdin);
+	freopen("output.txt", "w", stdout);
+	#endif
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	// num is the number taken as input
+	int num;
+	cin >> num;
+	for(int i = 1; i <= 10; i++){
+		cout << num << " x " << i << " = " << num*i << "\n";
+	}
+	return 0;
+}

Week1/Srilekha_Vinjamara/3a_cpp.cpp

@@ -0,0 +1,26 @@
+/* 
+c++ program to print traingle pattern
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+	#ifndef ONLINE_JUDGE
+	freopen("input.txt", "r", stdin);
+	freopen("output.txt", "w", stdout);
+	#endif
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+	int num;
+
+	// num is the input taken from user
+	cin >> num;
+	for(int i = 1; i <= num; i++){
+		for(int j = 1; j <= i; j++)
+			cout << "* ";
+		cout << "\n";
+	}
+	return 0;
+}

Week1/Srilekha_Vinjamara/3b_cpp.cpp

@@ -0,0 +1,28 @@
+/* 
+c++ program to print traingle pattern
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+	#ifndef ONLINE_JUDGE
+	freopen("input.txt", "r", stdin);
+	freopen("output.txt", "w", stdout);
+	#endif
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+	int num;
+
+	// num is the input taken from user
+	cin >> num;
+	for(int i = 1; i <= num; i++){
+		for(int k = num-1; k >= i; k--)
+			cout << " ";
+		for(int j = 1; j <= i; j++)
+			cout << "* ";
+		cout << "\n";
+	}
+	return 0;
+}