View Compilation Error

0_0_1676571_20171.cpp: In function `void tarjan(int)':
0_0_1676571_20171.cpp:54: error: `visit' undeclared (first use this function)
0_0_1676571_20171.cpp:54: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1676571_20171.cpp:56: error: `parent' undeclared (first use this function)
0_0_1676571_20171.cpp:59: error: 'struct node' has no member named 'v'
0_0_1676571_20171.cpp:69: error: 'struct node' has no member named 'v'