Find Factorial of long numbers

factorial_of_long_numbers.cpp

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+// Find factorial of large numbers
+// 100 factorial has 153 more
+// so, it cant be fit into long long data type also 
+// so, we use application of arrays
+#include<iostream>
+#include<vector>
+using namespace std;
+
+// this function will multiply the x with the previously stored arr values and update the arr
+
+int multiplyWith(vector<int> &arr,int arr_size,int x)
+{
+	int carry = 0;
+
+	for(int i=0 ; i<arr_size ; ++i)
+	{
+		int product = arr[i]*x + carry ;
+		arr[i] = product%10;
+		carry = product/10;
+	}
+	while(carry)
+	{
+		arr[arr_size] = carry%10;
+		arr_size++;
+		carry = carry/10;
+	}
+	return arr_size;
+}
+
+void findFact(int n)
+{
+	// factorial will be stored in this array
+	vector<int> arr(200);
+	arr[0] = 1; // intializing
+	int arr_size = 1; // array size will be in this variable
+
+	for(int i=2 ; i<=n ; ++i)
+	{
+		// this function will multiply 'i' values and store in the array
+		arr_size = multiplyWith(arr,arr_size,i);
+	}
+
+	// now we will print the array content from reverse side
+	for(int i=arr_size-1 ; i>=0 ; --i)
+	{
+		cout<<arr[i];
+	}
+	cout<<endl;
+}
+
+int main()
+{
+	int x;
+	cout<<"Enter a number: "<<endl;
+	cin>>x;
+	findFact(x);
+	return 0;
+}