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.
1 /** 2 * Definition for a binary tree node. 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 int minDepth(TreeNode* root) { 13 int left = 0; 14 int right = 0; 15 if (root == NULL) 16 return 0; 17 if (root->left != NULL) 18 left = minDepth(root->left); 19 if (root->right != NULL) 20 right = minDepth(root->right); 21 return 1 + (min(left, right) ? min(left, right) : max(left, right)); 22 } 23 };