View Compilation Error

0_0_26356741_22187.cpp:5:6: error: 'N' was not declared in this scope
 }mem[N*2], *h[N], *null, *tot; 
      ^
0_0_26356741_22187.cpp:5:15: error: 'N' was not declared in this scope
 }mem[N*2], *h[N], *null, *tot; 
               ^
0_0_26356741_22187.cpp: In function 'void init()':
0_0_26356741_22187.cpp:14:15: error: 'mem' was not declared in this scope
  null = tot = mem; 
               ^
0_0_26356741_22187.cpp:17:22: error: 'n' was not declared in this scope
  for(int i = 1; i <= n; i++) h[i] = null; 
                      ^
0_0_26356741_22187.cpp:17:30: error: 'h' was not declared in this scope
  for(int i = 1; i <= n; i++) h[i] = null; 
                              ^
0_0_26356741_22187.cpp: In function 'heap* merge(heap*, heap*)':
0_0_26356741_22187.cpp:23:27: error: 'swap' was not declared in this scope
  if(x->v < y->v) swap(x, y); 
                           ^
0_0_26356741_22187.cpp:25:59: error: 'swap' was not declared in this scope
  if(x->ch[0]->dis < x->ch[1]->dis) swap(x->ch[0], x->ch[1]); 
                                                           ^