View Compilation Error

0_0_15522218_28366.cpp: In function 'int solve()':
0_0_15522218_28366.cpp:10:18: error: 'strlen' was not declared in this scope
  int n = strlen(w);
                  ^
0_0_15522218_28366.cpp:52:33: error: 'strcmp' was not declared in this scope
  if(q.size() == 0 && strcmp(w, x) > 0)
                                 ^
0_0_15522218_28366.cpp: In function 'int main()':
0_0_15522218_28366.cpp:62:19: error: 'strcmp' was not declared in this scope
   if(strcmp(w, "#") == 0) break;
                   ^