refine the implementation of some dp algo
    1. add return increasing sequence for C12_3_LongestIncreasingSequence
    2. create a more complete test case for C6_5_ShortestPath and C12_4_GraphShortestPath
    3. fix bugs in C6_5_ShortestPath and C12_4_GraphShortestPath with
    Dijkstra algorithms
remove unused .settings file