题意

打印二叉树中和为某值的所有路径

分析

dfs 回溯即可。

/**
 * 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:
    vector<vector<int>> res;
    vector<int> tmp;
    bool isleaf(TreeNode* node){
        return node->left == NULL  && node->right == NULL;
    }
    void dfs(TreeNode* root, int sum, int target){
        if(isleaf(root)){
            sum += root->val;
            if(sum == target){
                tmp.push_back(root->val);
                res.push_back(tmp);
                tmp.pop_back();
                return;
            }
            return;
        }

        tmp.push_back(root->val);
        if(root->left != NULL)dfs(root->left, sum + root->val, target);
        if(root->right != NULL)dfs(root->right, sum + root->val, target);
        tmp.pop_back();
    }
    vector<vector<int>> findPath(TreeNode* root, int sum) {
        if(root == NULL)return res;
        dfs(root, 0, sum);
        return res;
    }
};