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### by Sumit Chourasia | Oct 06, 2020 | Category :coding | Tags : algorithmbinary-treedata-structureeasyleetcodetree #### Minimum Depth of Binary Tree - Tree - Easy - LeetCode

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.

Example:

Given binary tree [3,9,20,null,null,15,7],

3
/ \
9  20
/  \
15   7
return its minimum depth = 2.

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     public int val;
*     public TreeNode left;
*     public TreeNode right;
*     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
*         this.val = val;
*         this.left = left;
*         this.right = right;
*     }
* }
*/
public class Solution {
public int MinDepth(TreeNode root) {
if(root == null){
return 0;
}
if(root.left == null && root.right == null){
return 1;
}
int left = int.MaxValue;
int right = int.MaxValue;
if(root.left != null){
left = MinDepth(root.left);
}

if(root.right != null){
right = MinDepth(root.right);
}

return 1+ Math.Min(left, right);
}
}``````

Time Complexity: O(n)

Space Complexity: O(1)