【LeetCode】105 & 106 Construct Binary Tree from (Preorder and Inorder) || (Inorder and Postorder)Traversal

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
//105
class Solution {
public:
    void travel(TreeNode **root)
    {
        if(*root){
            travel(& ((*root) -> left));
            cout<<"val is "<<(*root)->val<<endl;
            travel(& ((*root) -> right));
        }
    }

    TreeNode* createTree(vector<int>& preorder, vector<int>& inorder, int preSta, int preEnd, int inSta, int inEnd)
    {
        if(preSta > preEnd || inSta > inEnd ) return NULL;
        TreeNode *root = new TreeNode(preorder[preSta]);
        int index;
        for(int i = inSta; i <= inEnd; i ++){
            if(inorder[i] == preorder[preSta]){
                index = i;
                break;
            }
        }
        root -> left = createTree(preorder, inorder, preSta + 1, preSta + index - inSta, inSta, index - 1);
        root -> right = createTree(preorder, inorder, preSta + index - inSta + 1, preEnd, index + 1, inEnd);
        return root;
    }

    TreeNode* buildTree(vector<int>& preorder, vector<int>& inorder) {
        TreeNode *root = createTree(preorder, inorder, 0, preorder.size() - 1, 0, inorder.size() - 1);
        TreeNode **r = &root;
        //travel(r);
        return root;
    }
};

//106.
class Solution {
public:
    TreeNode* createTree(vector<int>& inorder, vector<int>& postorder, int inSta, int inEnd, int postSta, int postEnd){
        if(inSta > inEnd || postSta > postEnd)
            return NULL;
        TreeNode* root = new TreeNode(postorder[postEnd]);
        int index;
        for(int i = inEnd; i >= inSta; i --){
            if(postorder[postEnd] == inorder[i]){
                index = i;
                break;
            }
        }
        root -> right = createTree(inorder, postorder, index + 1, inEnd, postEnd - (inEnd - index), postEnd - 1);
        root -> left = createTree(inorder, postorder, inSta, index - 1, postSta, postSta + (index - inSta - 1));
        return root;
    }
    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {
        TreeNode* root = createTree(inorder, postorder, 0, inorder.size() - 1, 0, postorder.size() - 1);
        return root;
    }
};