Minimum Depth of Binary Tree

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.

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/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int minDepth(TreeNode* root) { if(root == NULL) return 0; //if it is a leaf node if(root->left == NULL && root->right == NULL) return 1; int leftDepth, rightDepth; //if left is not NULL, recursively compute the depth of left else it is a internal node and it can't give the minDepth if(root ->left != NULL) leftDepth = minDepth(root->left); else leftDepth = INT_MAX; //if right is not NULL, recursively compute the depth of right tree else it is a internal node and it can't give the minDepth if(root ->right != NULL) rightDepth = minDepth(root->right); else rightDepth = INT_MAX; return 1 + min(leftDepth, rightDepth); } };