BigIntegerFactorial.cpp

Algebra-and-Numerical-Methods/LongIntegerFactorial.cpp

@@ -0,0 +1,53 @@
+
+#include <bits/stdc++.h>
+#define int long long
+#define vi vector<int>
+using namespace std;
+
+//This algorithm calculates the Factorial of very long Integers..
+
+void multiply(int num, int &posi, vector<int> &v)
+{
+    // to multiply every index element by num and adding remaining carry to the next index....
+    int carry=0;
+    for(int i=0; i<posi; i++)
+    {
+        int product=v[i]*num+ carry;
+        v[i]=product%10;
+        carry=product/10;
+    }
+
+    //Code for the carry which is still remaining even after multiplying by all the numbers....
+    while(carry)
+    {
+        v[posi]=carry%10;
+        carry=carry/10;
+        posi++;
+    }
+}
+
+void code()
+{
+    int n;
+    cin>>n;
+    vector<int> v(1000);
+    v[0]=1;
+
+
+    int posi=1;
+    for(int i=2; i<=n; i++)
+        multiply(i, posi, v);
+
+    //posi is the position till where an valid element is present at index....i.e the last element from starting of array...
+    for(int i=posi-1; i>=0; i--)
+        cout<<v[i];
+    cout<<endl;
+}
+
+signed main()
+{
+    cin.tie(NULL);
+    cout.tie(NULL);
+        code();
+    return 0;
+}