Q37

Consider the $\text{C}$ function $\text{foo}$ and the binary tree shown. typedef struct node { int val; struct node *left, *right; } node; int foo(node *p) { int retval; if (p == NULL) return 0; else { retval = p->val + foo(p->left) + foo(p->right); printf("%d ", retval); return retval; } }

When $\textsf{foo}$ is called with a pointer to the root node of the given binary tree, what will it print?