Create MinimumDepthOfABinaryTree.cpp

Author: Harshkr30

Diff for: MinimumDepthOfABinaryTree.cpp

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+// C++ program to find minimum depth of a given Binary Tree
+#include<bits/stdc++.h>
+using namespace std;
+
+// A Binary Tree Node
+struct Node
+{
+    int data;
+    struct Node *left, *right;
+};
+
+// A queue item (Stores pointer to node and an integer)
+struct qItem
+{
+   Node *node;
+   int depth;
+};
+
+// Iterative method to find minimum depth of Binary Tree
+int minDepth(Node *root)
+{
+    // Corner Case
+    if (root == NULL)
+        return 0;
+
+    // Create an empty queue for level order traversal
+    queue<qItem> q;
+
+    // Enqueue Root and initialize depth as 1
+    qItem qi = {root, 1};
+    q.push(qi);
+
+    // Do level order traversal
+    while (q.empty() == false)
+    {
+       // Remove the front queue item
+       qi = q.front();
+       q.pop();
+
+       // Get details of the remove item
+       Node *node = qi.node;
+       int depth = qi.depth;
+
+       // If this  is the first leaf node seen so far
+       // Then return its depth as answer
+       if (node->left == NULL && node->right == NULL)
+          return depth;
+
+       // If left subtree is not NULL, add it to queue
+       if (node->left != NULL)
+       {
+          qi.node  = node->left;
+          qi.depth = depth + 1;
+          q.push(qi);
+       }
+
+       // If right subtree is not NULL, add it to queue
+       if (node->right != NULL)
+       {
+          qi.node  = node->right;
+          qi.depth = depth+1;
+          q.push(qi);
+       }
+    }
+    return 0;
+}
+
+// Utility function to create a new tree Node
+Node* newNode(int data)
+{
+    Node *temp = new Node;
+    temp->data = data;
+    temp->left = temp->right = NULL;
+    return temp;
+}
+
+// Driver program to test above functions
+int main()
+{
+    // Let us create binary tree shown in above diagram
+    Node *root = newNode(1);
+    root->left = newNode(2);
+    root->right = newNode(3);
+    root->left->left = newNode(4);
+    root->left->right = newNode(5);
+
+    cout << minDepth(root);
+    return 0;
+}