View Compilation Error

0_0_17810933_26536.cpp: In function 'int merge(int, int)':
0_0_17810933_26536.cpp:54:7: error: no match for 'operator[]' (operand types are 'Node [100010]' and 'Node')
  if(ns[ns[lhs]].NPL > ns[ns[rhs]].NPL)
       ^
0_0_17810933_26536.cpp:54:25: error: no match for 'operator[]' (operand types are 'Node [100010]' and 'Node')
  if(ns[ns[lhs]].NPL > ns[ns[rhs]].NPL)
                         ^