View Compilation Error

0_0_38867009_30715.cpp: In function 'void Clear()':
0_0_38867009_30715.cpp:8:16: error: 'memset' was not declared in this scope
    8 | #define clr(x) memset(x, 0, sizeof x);
      |                ^~~~~~
0_0_38867009_30715.cpp:74:5: note: in expansion of macro 'clr'
   74 |     clr(hd) clr(h1) clr(dfn) clr(d) clr(d1) clr(f)
      |     ^~~
0_0_38867009_30715.cpp:7:1: note: 'memset' is defined in header '<cstring>'; did you forget to '#include <cstring>'?
    6 | #include <algorithm>
  +++ |+#include <cstring>
    7 | #define rep(i, s, t) for(int i=(s); i<=(t); ++i)