Minimum Depth of Binary Tree

【问题描述】

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.

【解决方案】

/**
 * Definition for binary tree
 * struct TreeNode {
 * int val;
 * struct TreeNode *left;
 * struct TreeNode *right;
  * };
 */
static int min(int a, int b)
{
    if(a<=b)
    {
        return a;
    }
    else
    {
        return b;
    }
}

static int minDepthDfs(struct TreeNode *root, bool hasbrother)
{
    if (!root)
    {
        return hasbrother ? INT_MAX : 0;
    }

    return 1 + min(minDepthDfs(root->left, root->right != NULL),
        minDepthDfs(root->right, root->left != NULL));
}

int minDepth(struct TreeNode *root) {
    return minDepthDfs(root, false);
}