Re: [閒聊] 每日leetcode

看板Marginalman作者sixB (6B)時間9月前 (2025/02/22 22:31)推噓0(0推 0噓 0→)

1028. traversal而已感覺要算簡單的medium== 寫起來醜醜的一個好好的遞回為啥被搞的這麼複雜看人家用stack好乾淨我就這樣了 /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode() : val(0), left(nullptr), right(nullptr) {} * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} * }; */ class Solution { public: TreeNode* recoverFromPreorder(string t) { TreeNode* root = new TreeNode(); TreeNode* nd = root; int cur = 0;// current depth int idx = 0; vector<int> ds, vs; while(true){ auto [d, val] = next(idx, t); if(val <= 0) break; ds.push_back(d); vs.push_back(val); } idx = 0; build(nd, cur, ds, vs, idx); return root; } void build(TreeNode* nd, int cur, vector<int>& ds, vector<int>& vs, int& idx){ if(idx >= ds.size()) return; if(ds[idx] == cur){ nd->val = vs[idx]; idx++; } if(idx >= ds.size()) return; if(ds[idx] > ds[idx-1]){ if(!nd->left){ nd->left = new TreeNode(); build(nd->left, cur+1, ds, vs, idx); } else{ nd->right = new TreeNode(); build(nd->right, cur+1, ds, vs, idx); } } if(idx >= ds.size()) return; if(ds[idx] > cur){ nd->right = new TreeNode(); build(nd->right, cur+1, ds, vs, idx); } } pair<int, int> next(int& idx, string& t){ int d = 0, val = 0, n = t.length(); if(idx >= n) return {-1, -1}; while(t[idx] == '-') { idx++; d++; } while(idx < n and t[idx] != '-') { val *= 10; val += t[idx] - '0'; idx++; } return {d, val}; } }; -- 很姆的咪姆之咪 http://i.imgur.com/5sw7QOj.jpg