View Compilation Error

0_0_16476614_18566.cpp: In function 'void init()':
0_0_16476614_18566.cpp:22:29: error: 'memset' was not declared in this scope
  memset(head,-1,sizeof(head));
                             ^
0_0_16476614_18566.cpp: In function 'void spfa(int)':
0_0_16476614_18566.cpp:36:26: error: 'memset' was not declared in this scope
  memset(vis,0,sizeof(vis));
                          ^