View Compilation Error

0_0_25739855_16981.cpp:19:10: error: no matching function for call to 'node::node()'
 }a[100010];
          ^
0_0_25739855_16981.cpp:19:10: note: candidates are:
0_0_25739855_16981.cpp:7:5: note: node::node(int, int)
     node(int a, int b) { l = a, r = b; }
     ^
0_0_25739855_16981.cpp:7:5: note:   candidate expects 2 arguments, 0 provided
0_0_25739855_16981.cpp:4:8: note: constexpr node::node(const node&)
 struct node
        ^
0_0_25739855_16981.cpp:4:8: note:   candidate expects 1 argument, 0 provided
0_0_25739855_16981.cpp:4:8: note: constexpr node::node(node&&)
0_0_25739855_16981.cpp:4:8: note:   candidate expects 1 argument, 0 provided