View Compilation Error

0_0_36596102_6365.cpp: In function 'int main()':
0_0_36596102_6365.cpp:5:24: error: 'memset' was not declared in this scope
  memset(p, 0, sizeof(p));
                        ^
0_0_36596102_6365.cpp:19:10: error: 'j' was not declared in this scope
     for (j=0; j <= n*(n-1)/2; j++)   //n*(n-1)/2能形成的最大交点数
          ^
0_0_36596102_6365.cpp:21:10: error: 'f' was not declared in this scope
      if (f[n][j])
          ^