CareerCup

You have a string of numbers, i.e. 123. You can insert a + or - sign in front of ever number, or you can leave it empty. Find all of the different possibilities, make the calculation and return the sum.
For example;
+1+2+3 = 6
+12+3 = 15
+123 = 123
+1+23 = 24
...
-1-2-3 = 6
...
Return the sum of all the results.

A new airline company is setting up operations and needs your help! They want to optimize their routes so as to cover a full list of cities, wile minimizing the cost of their operations.
You are provided with the number of N cities and with the costs of operating flights between some of the cities.
Can you design an algorithm that will return the list of routes that cover all the N cities at the minimum operational cost?

Assumtions:
1. not all direct routes between cities are possible, but all cities can be reached either directly of via intermediate cities. You are provided with the complete set of routes that are possible as input to your algorithm.
2. the costs of operating a route from any city to any other directly connected city is known and unique (i.e., no two costs between direct routes are the same)
3. the cost of operating a route from city X to city Y is equal to the cost of operating the route from city Y to city X

Your algorithm will get as input from stdin the following:
1. on the first line, the number of cities N
2. on the second line, the total number of possible routes K
3. on the subsequent K lines, the possible routes between cities and their operational cost, separated by spaces. Cities are integer numbers from 0 to N-1. costs are floats.

The output of your algorithm should be the list of routes chosen to be operated at the minimum cost, one route per line. After the list of routes, on the final line the total cost of operating all chosen routes should be printed.

What is the time complexity of the algorithm you've created?

Example:
Input
8
16
4 5 0.35
4 7 0.37
5 7 0.28
0 7 0.16
1 5 0.32
0 4 0.38
2 3 0.17
1 7 0.19
0 2 0.26
1 2 0.36
1 3 0.29
2 7 0.34
6 2 0.40
3 6 0.52
6 0 0.58
6 4 0.93

Output
0 7 0.16
2 3 0.17
1 7 0.19
0 2 0.26
5 7 0.28
4 5 0.35
6 2 0.40
1.81

You are given as input on stdin the number of employees in a company and their direct line management relations between each other. Each person in the company can directly line-manage maximum 2 other employees. The input from stdin has the following format:
1. on the first line, the number of employees
2. on the subsequent lines, the line management relations in the format «EmployeeM EmployeeN» - meaning EmployeeM manages EmployeeN (names are without spaces and spaces are used to separate the two names).
The input is correct (there are only direct management relations, no cycles).
For simplicity, the first line after the number of employees always contains the manager at the top of the hierarchy.
Write a program that reads the input file and then prints out the employees per level, in order of their importance (i.e. hierarchy):

Example:

Input:
6
Jon Mark
Jon David
Mark Paul
Paul Lee
Paul Steve

Output:
Jon
Mark David
Paul
Lee Steve

Input:
7
Jon Lee
Lee Paul
Paul Mark
Paul David
Lee Steve
Steve Mat

Output:
Jon
Lee
Paul Steve
Mark David Mat

Write function to calculate sum of first N powers of 2 starting from 1. You shouldn't use any built-in function for calculating power. Implement the most efficient solution.