Determine the Internal Path Length of a Tree (C++) -

well i'm down last function of program , i'm done. i've hit stump can't seem fix on own.

int tree::internalpathlength(node * r, int value) {     if(r->left == null && r->right == null)     {         return 0;     }     return value + internalpathlength(r->left, value+1) +          internalpathlength(r->right, value+1);  } 

i feel i'm close solution, know i'm missing something. think it's if statement , i've tried different combinations end getting crashed program or 0 answer.

any suggestions or appreciated ! thanks!

may works:

int tree::internalpathlength(node * r, int value) {     if(r->left == null && r->right == null)     {         return 0;     }     return value + ( r->left? internalpathlength(r->left, value+1):0 )                  + ( r->right? internalpathlength(r->right, value+1):0 );  } 

or add null check node

int tree::internalpathlength(node * r, int value) {     if (r == null ) return 0;     if(r->left == null && r->right == null)     {         return value +1;     }     return value + internalpathlength(r->left, value+1) +          internalpathlength(r->right, value+1);  }