二分木で最も深い左葉を見つけるためのC++プログラム

左の子と右の子として指定された、最大2つの子を持つ二分木。これは、二分木で最も深い左葉を見つけるためのC++プログラムです

アルゴリズム

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.

サンプルコード

#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;
}

出力

The deepest left leaf is 6