leetCode_根据前序、中序建树以及根据中序、后序建树

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1、根据前序、中序建树

    TreeNode * build(vector<int>& preorder,int pleft,int pright,vector<int>& inorder,int ileft,int iright)    {        if(pleft>pright || ileft>iright) return NULL;        int i,j,k;        for(i=ileft;i<=iright;i++) if(preorder[pleft]==inorder[i]) break;        TreeNode * node=new TreeNode(preorder[pleft]);        int size=i-ileft;        node->left=build(preorder,pleft+1,pleft+size,inorder,ileft,i-1);        node->right=build(preorder,pleft+size+1,pright,inorder,i+1,iright);        return node;    }    TreeNode* buildTree(vector<int>& preorder, vector<int>& inorder) {        return build(preorder,0,preorder.size()-1,inorder,0,inorder.size()-1);    }

2、根据中序、后序建树

    TreeNode * build(vector<int>& inorder,int ileft,int iright,vector<int>& postorder,int pleft,int pright)    {        if(pleft>pright || ileft>iright) return NULL;        int i,j,k;        for(i=ileft;i<=iright;i++) if(postorder[pright]==inorder[i]) break;        TreeNode * node=new TreeNode(postorder[pright]);        int size=i-ileft;        node->left=build(inorder,ileft,i-1,postorder,pleft,pleft+size-1);        node->right=build(inorder,i+1,iright,postorder,pleft+size,pright-1);        return node;    }    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {        return build(inorder,0,inorder.size()-1,postorder,0,postorder.size()-1);    }

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