View Compilation Error

0_0_17415032_3215.cpp: In function 'void clear()':
0_0_17415032_3215.cpp:28:31: error: 'memset' was not declared in this scope
  memset(head, -1, sizeof(head));
                               ^
0_0_17415032_3215.cpp: In function 'int SPFA(int, int)':
0_0_17415032_3215.cpp:46:27: error: 'memset' was not declared in this scope
  memset(in, 0 , sizeof(in));
                           ^