• Question
• Solution

Question

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.

Solution

Result: Accepted Time: 4 ms

Here should be some explanations.

int minDepth(struct TreeNode* root) {
    if(root == NULL)
        return 0;
    if(!root->left && !root->right)
        return 1;
    int a = 0x07fffffff,b = 0x7fffffff;
    if(root->left)
        a = minDepth(root->left);
    if(root->right)
        b = minDepth(root->right);
    return (a>b?b:a)+1;
}

Complexity Analytics

• Time Complexity: $O(n)$
• Space Complexity: $O(1)$