2003B Should Print the Minimum-Cost Solution

Function:
`void solve(vector<int> src, vector<int> dst)` @ acm/finals/2003/B.cc

Issue:
In this problem, 'For each test case, print a line containing the case number and a decimal integer representing a **minimum-cost** set of switches that need to be flipped to convert the row of bulbs from initial state to final state.'

But this function just prints the smallest decimal solution.
