标签：style blog http ar io color os sp on
这题要收费了。只能网上看题目，我等屌丝也没法OJ测试了。网上看了后发现其实并非独创，其他的方也有类似的题。例如在这里，CareerCup上
先用了递归的想法，
TreeNode *ans; TreeNode *helper156(TreeNode *root) { if (!root -> left && !root -> right) { ans = root; return root; } TreeNode *parent = UpsideDown(root -> left); parent -> left = root -> right; parent -> right = root; root -> left = NULL; root -> right = NULL; return parent -> right; } TreeNode *UpsideDown(TreeNode *root) { if (root) helper156(root); return ans; }
在这里提到如果是非递归的那么和反转链表差不多Reverse Linked List II
TreeNode *UpsideDown2(TreeNode *root) { if (!root -> left && !root -> right) return root; TreeNode *parent = NULL, *parentRight = NULL, *p = root; while(p) { TreeNode *left = p -> left; p -> left = parentRight; parentRight = p -> right; p -> right = parent; parent = p; p = left; } return parent; }
不用递归还是挺妙的啊。
leetcode binary tree upside down
标签：style blog http ar io color os sp on
原文地址：http://www.cnblogs.com/higerzhang/p/4173520.html
