View Compilation Error

0_0_29225482_22998.cpp: In function 'void init()':
0_0_29225482_22998.cpp:15:31: error: 'memset' was not declared in this scope
  memset(head, -1, sizeof(head));
                               ^
0_0_29225482_22998.cpp: In function 'void solve()':
0_0_29225482_22998.cpp:50:28: error: 'memset' was not declared in this scope
  memset(dfn, 0, sizeof(dfn));
                            ^