Print from recursion combination with list in C

Question

I want to understand the following code: struct element{ element *a1; element *a2; int value; }; void main(){ element e6 = { NULL, NULL, 6 }; element e2 = { NULL, NULL, 2 }; element e4 = { NULL, NULL, 4 }; element e7 = { &e6, NULL, 7 }; element e9 = { NULL, NULL, 9 }; element e3 = { &e2, &e4, 3 }; element e8 = { &e7, &e9, 8 }; element e5 = { &e3, &e8, 5 }; cout << CountList(&e5) << endl; return;} int CountList(element *e){ int c=1; if(e){ c=c+CountList(e->a1); c=c+CountList(e->a2); return c;} return 0; } the count is 8. But how can I understand the recursion line ?? my Idea was, that the Count must be 6, because the recursion function are called only 4 times. The Compiler says 8, which is already the correct solution. But why?? JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

This is a tree e5 / \ e3 e8 / \ / \ e2 e4 e7 e9 | e6 The recursive function starts from e5, calls itself with e3 first, which in turn calls with e2, another call with NULL which returns (to e2). From e2 a call on the other side which is NULL also, then returns (to e3). From e3, a call to e4, which has only NULL children and returns (to e3). From there, e3 returns to e5, which calls the other side (e8)... Each non-NULL element counts itself as 1, added to the non-NULL children. Which gives 8 total. The number of elements in the tree. The number of calls to the recursive function is at least 8, to visit all children. If you count the calls with a NULL element (9), that makes a total number of calls of 17.