# 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:
lvel is level of current node.
maxlvel is pointer to the deepest left leaf node found so far
isLeft Indicates that this node is left child of its parent
resPtr 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

Live Demo

#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

Samual Sam

Learning faster. Every day.

Updated on: 30-Jul-2019

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