/usr/bin/ld: /tmp/ccVJJbTH.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/cc5F7GcI.o:walk.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/cc5F7GcI.o: in function `main':
walk.cpp:(.text.startup+0x265): undefined reference to `min_distance(std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, int, int)'
/usr/bin/ld: /tmp/ccVJJbTH.o: in function `main':
grader.cpp:(.text.startup+0x395): undefined reference to `min_distance(std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, int, int)'
collect2: error: ld returned 1 exit status