Merge pull request #2776 from Abe0770/main

Create 0111-minimum-depth-of-binary-tree.cpp

Author: MHamiid

Diff for: cpp/0111-minimum-depth-of-binary-tree.cpp

@@ -0,0 +1,51 @@
+/*
+  Given a binary tree, find its minimum depth.
+
+  The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.
+
+  Note: A leaf is a node with no children.
+
+  Ex. Input: root = [3,9,20,null,null,15,7]
+      Output: 2
+
+  Time  : O(N)
+  Space : O(N)
+*/
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+    int minDepth(TreeNode* root) {
+        if(!root) 
+            return 0;
+        int count = 1;
+        queue <TreeNode*> q;
+        q.push(root);
+        while(!q.empty()) {
+            int size = q.size();
+            for(int i = 0 ; i < size ; i++) {
+                TreeNode* front = q.front();
+                if(!front -> left && !front -> right)
+                    return count;
+                if(front -> left)
+                    q.push(front -> left);
+                if(front -> right)
+                    q.push(front -> right);
+
+                q.pop();
+            }
+            count++;
+        }
+        return count;
+    }
+};