Post order traversal sequence of binary search tree

Title Description

• Input an integer array to determine whether the array is the result of the subsequent traversal of a binary search tree. If Yes, output Yes; otherwise, output No. Suppose that any two numbers of the input array are different from each other.

C++ code

class Solution {
public:
    bool VerifySquenceOfBST(vector<int> sequence)
    {
        if(sequence.size()==0)
        {
            return false;
        }
        else
        {
            int len = sequence.size();
            vector<int>left,right;
            int i = 0;
            for(;i<len-1;i++)
            {
                if(sequence[i]<sequence[len-1])
                {
                    left.push_back(sequence[i]);
                }
                else
                {
                    break;
                }
            }
            for(;i<len-1;i++)
            {
                if(sequence[i]>sequence[len-1])
                {
                    right.push_back(sequence[i]);
                }
                else
                {
                    return false;
                }
            }
            bool L = true;
            bool R = true;
            if(left.size()!=0)
            {
                L = VerifySquenceOfBST(left);
            }
            if(right.size()!=0)
            {
                R = VerifySquenceOfBST(right);
            }
            return L && R;
        }
    }
};

Path with a certain value in a binary tree

Title Description

• Input the following node and an integer of a binary tree, and print out all paths in which the sum of node values in the binary tree is the input integer. Path is defined as a path from the root node of the tree to the node that the leaf node passes through. (Note: in the list of returned values, the array with large array length is first)

C++ code

/*
struct TreeNode {
	int val;
	struct TreeNode *left;
	struct TreeNode *right;
	TreeNode(int x) :
			val(x), left(NULL), right(NULL) {
	}
};*/
class Solution {
public:
    vector<vector<int> > FindPath(TreeNode* root,int expectNumber) 
    {
        vector<vector<int>>res;
        vector<int>out;
        helper(root,expectNumber,out,res);
        return res;
    }
    void helper(TreeNode*node,int sum,vector<int>&out,vector<vector<int>>&res)
    {
        if(node==NULL)
        {
            return;
        }
        out.push_back(node->val);
        if(sum==node->val && node->left==NULL && node->right==NULL)
        {
            res.push_back(out);
        }
        helper(node->left,sum-node->val,out,res);
        helper(node->right,sum-node->val,out,res);
        out.pop_back();
    }
};