leetcode 105 & 106

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105

c++(16ms)

TreeNode* get(vector<int>& preorder,int p_start,int p_end, vector<int>& inorder,int i_start,int i_end) {        TreeNode*root = new TreeNode(preorder[p_start]);        int pos = distance(inorder.begin(),find(inorder.begin() + i_start,inorder.begin()+i_end,preorder[p_start]));        int l_size = pos - i_start,r_size = i_end - pos;        if(l_size) root->left  = get(preorder, p_start+1, p_start+l_size,inorder , i_start  , pos-1);        if(r_size) root->right = get(preorder, p_start+l_size+1,p_start+l_size+r_size,inorder , pos+1,i_end);        return root;    }    TreeNode* buildTree(vector<int>& preorder, vector<int>& inorder) {        if(!preorder.size()) return nullptr;        return get(preorder,0,preorder.size()-1,inorder,0,inorder.size()-1);    }

106

c++

TreeNode* get(vector<int>& inorder,int i_start,int i_end,vector<int>& postorder,int p_start,int p_end) {        TreeNode* root = new TreeNode(postorder[p_end]);        int pos = distance(inorder.begin(),find(inorder.begin()+i_start,inorder.begin()+i_end,postorder[p_end]));        int l_size = pos - i_start,r_size = i_end - pos;        if(l_size) root->left = get(inorder,i_start,pos-1,postorder,p_start,p_start+l_size-1);        if(r_size) root->right = get(inorder,pos+1,i_end,postorder,p_start+l_size,p_start+l_size+r_size-1);        return root;    }    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {        if(!inorder.size()) return nullptr;        return get(inorder,0,inorder.size()-1,postorder,0,postorder.size()-1);    }

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