/tmp/ccYyc1a4.o: In function `main':
main.cpp:(.text+0xd9): undefined reference to `size(opaque_list*)'
main.cpp:(.text+0x13a): undefined reference to `memberOf(opaque_list*, int)'
main.cpp:(.text+0x1a0): undefined reference to `dot(opaque_list*, opaque_list*)'
main.cpp:(.text+0x1e9): undefined reference to `isIncreasing(opaque_list*)'
main.cpp:(.text+0x235): undefined reference to `reverse(opaque_list*)'
main.cpp:(.text+0x2a1): undefined reference to `append(opaque_list*, opaque_list*)'
main.cpp:(.text+0x2f3): undefined reference to `isArithmeticSequence(opaque_list*)'
main.cpp:(.text+0x33f): undefined reference to `filter_odd(opaque_list*)'
main.cpp:(.text+0x3a3): undefined reference to `filter(opaque_list*, bool (*)(int))'
main.cpp:(.text+0x3f5): undefined reference to `unique(opaque_list*)'
main.cpp:(.text+0x477): undefined reference to `insert_list(opaque_list*, opaque_list*, unsigned int)'
main.cpp:(.text+0x4e1): undefined reference to `chop(opaque_list*, unsigned int)'
main.cpp:(.text+0x533): undefined reference to `tree_sum(opaque_tree*)'
main.cpp:(.text+0x594): undefined reference to `tree_search(opaque_tree*, int)'
main.cpp:(.text+0x5e0): undefined reference to `depth(opaque_tree*)'
main.cpp:(.text+0x629): undefined reference to `tree_max(opaque_tree*)'
main.cpp:(.text+0x672): undefined reference to `traversal(opaque_tree*)'
main.cpp:(.text+0x6c4): undefined reference to `tree_hasMonotonicPath(opaque_tree*)'
main.cpp:(.text+0x728): undefined reference to `tree_allPathSumGreater(opaque_tree*, int)'
main.cpp:(.text+0x78c): undefined reference to `tree_allPathSumGreater(opaque_tree*, int)'
main.cpp:(.text+0x7f2): undefined reference to `covered_by(opaque_tree*, opaque_tree*)'
main.cpp:(.text+0x858): undefined reference to `contained_by(opaque_tree*, opaque_tree*)'
main.cpp:(.text+0x8bc): undefined reference to `insert_tree(int, opaque_tree*)'
collect2: error: ld returned 1 exit status