LeetCode OJ--Path Sum *

https://oj.leetcode.com/problems/path-sum/

树的深搜，求从根到叶子的路径。

记住深搜的样子

#include <iostream>
using namespace std;
struct TreeNode {
     int val;
     TreeNode *left;
     TreeNode *right;
     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 };


class Solution {
public:
    bool hasPathSum(TreeNode *root, int sum) {
        //null
        if(root == NULL )
            return false;

        //leaf node
        if(root->left == NULL && root->right == NULL && root->val == sum)
            return true;
        if(root->left == NULL && root->right == NULL)
            return false;

        //not leaf node
        if(root->left ||root->right)
         {
             bool ans = false;

            if(root->left)
            {
                ans = hasPathSum(root->left, sum - root->val);
                if(ans == true)
                return true;
            }
            if(root->right)
            {
                ans = hasPathSum(root->right, sum-root->val);
                if(ans == true)
                return true;
            }
            return false;
         }
        return false;
    }
};

int main()
{
    TreeNode *n1 = new TreeNode(1);
    TreeNode *n2 = new TreeNode(-2);
    TreeNode *n3 = new TreeNode(-3);
    TreeNode *n4 = new TreeNode(1);
    TreeNode *n5 = new TreeNode(3);
    TreeNode *n6 = new TreeNode(-2);
    TreeNode *n7 = new TreeNode(-1);
    n1->left = n2;
    n1->right = n3;
    n2->left = n4;
    n2->right = n5;
    n3->left = n6;
    n3->right = NULL;
    n4->left = n7;
    class Solution myS;
    cout<<myS.hasPathSum(n1,2);
    return 0;
}