leetcode笔记-Path Sum

关于路径问题：

1.输出所有的路径

<pre name="code" class="cpp"> void findPath(vector<vector<int>> &ret,vector<int> tmp, TreeNode* root)
    {
        if(root==NULL) return;
        tmp.push_back(root->val);
        if(root->left == NULL && root->right == NULL)
        {
            ret.push_back(tmp);
            return;
        }
        if(root->left!=NULL) findPath(ret,tmp,root->left);
        if(root->right!=NULL) findPath(ret,tmp,root->right);
        //tmp.pop_back();
    }

//这个程序可以输出从根节点到任意叶节点的路径

2.关于路径和的问题

2.1 返回真假

class Solution {
public:
    bool hasPathSum(TreeNode* root, int sum) {
        if(root==NULL) return false;
        if(root->val==sum&&root->left==NULL&&root->right==NULL) return true;
        return hasPathSum(root->left,sum-root->val)||hasPathSum(root->right,sum-root->val);
    }
    
};

2.2 返回路径

<pre name="code" class="cpp">class Solution {
public:
    vector<vector<int>> pathSum(TreeNode* root, int sum) {
        vector<vector<int>> ret;
        vector<vector<int>> result;
        vector<int> tmp;
        findPath(ret,tmp,root);
        while(!ret.empty())
        {
            vector<int> p;
            int j=0;
            p=ret.back();
            cout<<p[1]<<endl;
            for(int i=0;i<p.size();i++)
            {
                j=j+p[i];
                cout<<p[i]<<endl;
                //p.pop_back();
                //cout<<j<<endl;
            }
            if(j==sum) result.push_back(p);
            ret.pop_back();
        }
        return result;
        
    }
    
    void findPath(vector<vector<int>> &ret,vector<int> tmp, TreeNode* root)
    {
        if(root==NULL) return;
        tmp.push_back(root->val);
        if(root->left == NULL && root->right == NULL)
        {
            ret.push_back(tmp);
            return;
        }
        if(root->left!=NULL) findPath(ret,tmp,root->left);
        if(root->right!=NULL) findPath(ret,tmp,root->right);
        //tmp.pop_back();
    }
};