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【leetcode】105. 從前序與中序遍歷序列構造二叉樹

struct TreeNode* buildTree(int* preorder, int preorderSize, int* inorder, int inorderSize){
    if(preorderSize==0 || inorderSize==0)
        return NULL;
    struct TreeNode** stArr=(struct TreeNode**)calloc(preorderSize,sizeof(struct TreeNode*));
    int top=-1, pPst=0, iPst=0, flag=iPst;
    struct
TreeNode* root=(struct TreeNode*)calloc(1,sizeof(struct TreeNode)); struct TreeNode* temp=root; root->val=preorder[pPst++]; stArr[++top]=root; while(pPst<preorderSize && iPst<inorderSize){ while(top>=0 && stArr[top]->val == inorder[iPst]){ temp
=stArr[top--]; iPst++; } struct TreeNode* node=(struct TreeNode*)calloc(1,sizeof(struct TreeNode)); node->val=preorder[pPst++]; stArr[++top]=node; if(flag != iPst) temp->right=node; else temp->left=node; temp
=node; flag=iPst; } return root; }