View Compilation Error

0_0_20616372_14186.cpp: In function 'void Dijkstra(int)':
0_0_20616372_14186.cpp:34:29: error: 'pre' was not declared in this scope
     memset(pre_v, 0, sizeof(pre
                             ^
0_0_20616372_14186.cpp:34:29: error: expected ')' at end of input
0_0_20616372_14186.cpp:34:29: error: expected '}' at end of input