C++ Program to Find Deepest Left Leaf in a Binary Tree

A binary tree which has at most two children, specified as left child and right child. This is a C++ Program to Find Deepest Left Leaf in a Binary Tree

Algorithm

Begin.
   function deepestLLeafutil() find the deepest left leaf in a given
   binary tree:  
      <strong>lvel </strong>is level of current node.
      <strong>maxlvel </strong>is pointer to the deepest left leaf node found so far  
      <strong>isLeft </strong>Indicates that this node is left child of its parent  
      <strong>resPtr </strong>is Pointer to the result  
      If root is equal to Null then  
         Return.  
      Update result if this node is having a left leaf and its level is
      more than the max level of the current result.  
      Recursively call function deepestLLeafutil() for left and right subtrees. 
End.

Example Code

#include <iostream>
using namespace std;
struct n {
   int v;
   n *l, *r;
};
void deepestLLeafutil(n *root, int lvel, int *maxvel, bool isLeft, n **resPtr) {
   if (root == NULL)
      return;
   if (isLeft && !root->l && !root->r && lvel > *maxvel) {
      *resPtr = root;
      *maxvel = lvel;
      return;
   }
   deepestLLeafutil(root->l, lvel + 1, maxvel, true, resPtr);
   deepestLLeafutil(root->r, lvel + 1, maxvel, false, resPtr);
}
n* deepestLLeaf( n *root) {
   int maxlevel = 0;
   n *res = NULL;
   deepestLLeafutil(root, 0, &maxlevel, false, &res);
   return res;
}
n *newnode(int d) {
   n *t = new n;
   t->v = d;
   t->l = t->r = NULL;
   return t;
}
int main() {
   n* root = newnode(9);
   root->l = newnode(7);
   root->r = newnode(10);
   root->l->l = newnode(6);
   root->r->l= newnode(8);
   root->r->r = newnode(19);
   root->r->l->r = newnode(4);
   root->r->r->r = newnode(20);
   n *res = deepestLLeaf(root);
   if (res)
      cout << "The deepest left leaf is " << res->v;
   else
      cout << "There is no left leaf in the given tree";
   return 0;
}

Output

The deepest left leaf is 6