LeetCode 113:Path Sum II

Posted 2020-09-21 yutingliuyl

Given a binary tree and a sum, find all root-to-leaf paths where each path‘s sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5
             /             4   8
           /   /           11  13  4
         /  \    /         7    2  5   1

return

[
   [5,4,11,2],
   [5,8,4,5]
]

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 class Solution {
 public:
	 vector<vector<int>> pathSum(TreeNode* root, int sum) {
		 vector<vector<int>> res;
		 vector<int> tmp; //保存中间结果
		 tmpFunction(root, sum, tmp, res);
		 return res;
	 }

	 void tmpFunction(TreeNode* root, int sum, vector<int> &tmp, vector<vector<int>>&res){
		 if (root == NULL) return;
		 tmp.push_back(root->val);
		 if (root->left == NULL && root->right == NULL){
			 if (root->val == sum)
				 res.push_back(tmp);
		 }
		 tmpFunction(root->left, sum - root->val, tmp, res);
		 tmpFunction(root->right, sum - root->val, tmp, res);
		 tmp.pop_back();
	 }
 };

#include<iostream>
#include<new>
#include<vector>
using namespace std;

//Definition for binary tree
struct TreeNode
{
	int val;
	TreeNode *left;
	TreeNode *right;
	TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

class Solution
{
public:
	vector<vector<int> > pathSum(TreeNode *root, int sum)
	{
		vector<vector<int> > path;
		vector<int> tmp;
		hasPathSum(root, sum, path, tmp);
		return path;
	}
	void hasPathSum(TreeNode *root, int sum, vector<vector<int> > &path, vector<int> tmp)
	{
		if (root == NULL)
			return;
		tmp.push_back(root->val);
		if (root->left == NULL&&root->right == NULL && (sum - root->val) == 0)
		{
			path.push_back(tmp);
		}
		if (root->left)
			hasPathSum(root->left, sum - root->val, path, tmp);
		if (root->right)
			hasPathSum(root->right, sum - root->val, path, tmp);

		tmp.pop_back();
	}
	void createTree(TreeNode *&root)
	{
		int i;
		cin >> i;
		if (i != 0)
		{
			root = new TreeNode(i);
			if (root == NULL)
				return;
			createTree(root->left);
			createTree(root->right);
		}
	}
};
int main()
{
	Solution s;
	TreeNode *root;
	s.createTree(root);
	vector<vector<int> > path = s.pathSum(root, 22);
	for (auto a : path)
	{
		for (auto v : a)
			cout << v << " ";
		cout << endl;
	}
	system("pause");
	return 0;
}