Added electricity bill calc program

Coding/C++/electricity_bill_calculator

@@ -0,0 +1,44 @@
+#include <iostream>
+using namespace std;
+
+int main()
+{
+    float pm,cm,diff,net,j;
+    cout << "Enter last month unit consumption: ";
+    cin >> pm;
+    cout << "Enter current month unit consumption: ";
+    cin >>cm;
+    diff=cm-pm;
+    if (diff>0)
+    {
+        if(diff<=100)
+        {
+            j=diff*2;
+        }
+        else if(diff>100 && diff<=200)
+        {
+            j=diff-100;
+            j=j*3;
+            net=j+200;
+        }
+        else if(diff>200 && diff<=300)
+        {
+            j=diff-200;
+            j=j*4;
+            net=j+500;
+        }
+        else
+        {
+            j=diff-300;
+            j=j*5;
+            net=j+900;
+        }
+        net=net+100;
+        cout << "Net unit consumption: " << diff << "\nTotal Bill: ₹" << net;
+    }
+    else
+    {
+        cout << "Invalid Input!";
+    }
+    return 0;
+}