foo.cc: In function 'int dfs(int, int, result)':
foo.cc:24:3: error: 'itoa' was not declared in this scope
   24 |   itoa(now_state, str, 10);
      |   ^~~~
foo.cc:26:16: error: 'strlen' was not declared in this scope
   26 |   for (int j = strlen(str) - 1; j >= 0; j--) {
      |                ^~~~~~
foo.cc:7:1: note: 'strlen' is defined in header '<cstring>'; did you forget to '#include <cstring>'?
    6 | #include <stdlib.h>
  +++ |+#include <cstring>
    7 | using namespace std;
foo.cc:22:7: warning: unused variable 'tmp' [-Wunused-variable]
   22 |   int tmp = now_state;
      |       ^~~
foo.cc: In function 'int main()':
foo.cc:51:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   51 |   scanf("%d", &tmp);
      |   ~~~~~^~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务