题解 | 二叉树的最小深度

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int ans = 1e7;
    void dfs(TreeNode* head, int num)
    {
        if (!head) return; // 空节点直接返回
        if(ans <= num)return;
        if(!head->left && !head->right)
        {
            ans = min(ans, num + 1);
            return;
        }
        dfs(head->left, num + 1);
        dfs(head->right, num + 1);
    }
    int run(TreeNode* root) {
        // write code here
        if(!root)
        {
            return 0;
        }
        TreeNode* head = root;
        dfs(head, 0);
        return ans;
    }
};