View Compilation Error

0_0_38089895_6203.cpp: In function 'int main()':
0_0_38089895_6203.cpp:75:37: error: 'memset' was not declared in this scope
         memset(world,0,sizeof(world));
                                     ^
0_0_38089895_6203.cpp:77:1: error: 'a' was not declared in this scope
 a
 ^
0_0_38089895_6203.cpp:78:25: error: 'i' was not declared in this scope
         for (int i = 1; i <= N; ++i)
                         ^