Bit wise calculation of a power b

bit wise calculation of a power b.c

@@ -0,0 +1,24 @@
+#include<stdio.h>
+int main()
+{
+        int a,b,mod,result=1;
+        scanf("%d %d %d",&a,&b,&mod);
+        int bit=8*sizeof(b);
+
+        for(int i=0;i<bit;i++)
+        {
+                printf("%d\n",b);
+                if(1&b)
+                {
+                        result=(a*result)%mod;
+                }
+                a=(a*a)%mod;
+                b>>=1;
+
+                printf("%d:no. of iletrations\n",i);
+                printf("result:%d\n",result);
+        }
+        printf("%d\n",result);
+        return 0;
+}
+

large factorial.c

@@ -0,0 +1,68 @@
+// C++ program to compute factorial of big numbers 
+#include<iostream> 
+using namespace std; 
+
+// Maximum number of digits in output 
+#define MAX 500 
+
+int multiply(int x, int res[], int res_size); 
+
+// This function finds factorial of large numbers 
+// and prints them 
+void factorial(int n) 
+{ 
+	int res[MAX]; 
+
+	// Initialize result 
+	res[0] = 1; 
+	int res_size = 1; 
+
+	// Apply simple factorial formula n! = 1 * 2 * 3 * 4...*n 
+	for (int x=2; x<=n; x++) 
+		res_size = multiply(x, res, res_size); 
+
+	cout << "Factorial of given number is \n"; 
+	for (int i=res_size-1; i>=0; i--) 
+		cout << res[i]; 
+} 
+
+// This function multiplies x with the number 
+// represented by res[]. 
+// res_size is size of res[] or number of digits in the 
+// number represented by res[]. This function uses simple 
+// school mathematics for multiplication. 
+// This function may value of res_size and returns the 
+// new value of res_size 
+int multiply(int x, int res[], int res_size) 
+{ 
+	int carry = 0; // Initialize carry 
+
+	// One by one multiply n with individual digits of res[] 
+	for (int i=0; i<res_size; i++) 
+	{ 
+		int prod = res[i] * x + carry; 
+
+		// Store last digit of 'prod' in res[] 
+		res[i] = prod % 10; 
+
+		// Put rest in carry 
+		carry = prod/10;	 
+	} 
+
+	// Put carry in res and increase result size 
+	while (carry) 
+	{ 
+		res[res_size] = carry%10; 
+		carry = carry/10; 
+		res_size++; 
+	} 
+	return res_size; 
+} 
+
+// Driver program 
+int main() 
+{ 
+	factorial(100); 
+	return 0; 
+} 
+