Merge pull request #808 from Karnika06/Devincept11

Added Truck tour problem (Hackerrank)

Author: noviicee

Data Structures/Queues/Truck_tour.cpp

@@ -0,0 +1,88 @@
+/*
+
+Implementation of Truck tour problem from Hackerrank
+
+Suppose there is a circle. There are N petrol pumps on that circle. 
+Petrol pumps are numbered 0 to (N-1) (both inclusive). You have two pieces 
+of information corresponding to each of the petrol pump:
+(1) the amount of petrol that particular petrol pump will give, and
+(2) the distance from that petrol pump to the next petrol pump.
+
+Initially, you have a tank of infinite capacity carrying no petrol. 
+You can start the tour at any of the petrol pumps. Calculate the first 
+point from where the truck will be able to complete the circle. Consider 
+that the truck will stop at each of the petrol pumps. The truck will 
+move one kilometer for each litre of the petrol.
+
+Link to the problem: https://www.hackerrank.com/challenges/truck-tour/problem
+*/
+
+#include<iostream>
+using namespace std;
+
+int main()
+{
+    int n;
+    cin >> n;
+    int petrol[n], distance[n];
+    for (int i = 0; i < n; i++)
+    {
+        cin >> petrol[i];
+        cin >> distance[i];
+    }
+    //the amount of petrol left in the truck
+    int amountofpetrol = 0;        
+    
+    //the total amount of petrol we were short of in each petrol pump
+    int previous = 0; 
+	
+	//stores the index of the starting point      	   
+    int startindex = 0;   
+	         
+    for(int i = 0; i < n; i++)
+    {
+    	//calculating amount of petrol left
+        amountofpetrol += (petrol[i] - distance[i]);
+		
+		//true means that route does not exists from the current starting point	
+        if(amountofpetrol < 0)		
+        {
+            previous = previous + amountofpetrol;
+            amountofpetrol = 0;
+            
+            //start agaain from starting point
+            startindex = i + 1;		
+        }
+    }
+    //returns starting point
+    cout << startindex <<endl;		
+    return 0;
+}
+
+/* Time complexity: O(n)
+
+Example 1:
+
+Sample Input
+
+3
+1 5
+10 3
+3 4
+
+Sample Output
+
+1
+
+Example 2:
+
+Sample Input
+
+3
+6 4
+3 6
+7 3
+
+Sample Output
+
+2*/