在职刷题打卡

刷题大概5个月了 但是才刷了290题 进度有点慢。。发个打卡贴求大米求鼓励！
目标：每天能复习1-2个旧题 ＋ 1－2个没做过的新题

之前发错板块了，新手也不懂怎么挪板块，就重新发到这里。争取每天都来更新！
顺便求加分啊！最近要面试，但积分太少好多面经都看不到、真是好着急啊

Add and Search Word - Data structure design。 这个trie的解法竟然只比5%的submissions快，难道可以再优化时间吗？

struct Node{
    bool isWord;
    unordered_map<char, Node*> children;
    Node(){
        isWord = false;
    }
};
class WordDictionary {
public:
    /** Initialize your data structure here. */
    WordDictionary() {
        root = new Node();
    }
   
    /** Adds a word into the data structure. */
    void addWord(string word) {
        Node* dummy = root;
        for(char c: word){
            if(!dummy->children[c])
                dummy->children[c] = new Node();
            dummy = dummy->children[c];
        }
        dummy->isWord = true;
    }
   
    /** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */
    bool search(string word) {
        Node* dummy = root;
        return help(word, 0, dummy);
    }
   
    bool help(string &word, int id, Node* root){
        if(!root)
            return false;
        if(id == word.size())
            return root->isWord;
        unordered_map<char, Node*> cur_children = root->children;
        char c = word[id];
        if(c != '.')
            return help(word, id + 1, cur_children[c]);
        for(auto it = cur_children.begin(); it != cur_children.end(); it++){
            if(help(word, id + 1, it->second))
                return true;
        }
        return false;
    }
private:
    Node* root;
};

8/3

• Serialize and Deserialize Binary Tree
• 670        Maximum Swap
• 986        nterval List Intersections
• 489        Robot Room Cleaner
• 199        Tree right view
• 76        find the minimum window in S which will contain all the characters in T i
• 239        Sliding Window Maximum
• 238        Product of Array Except Self
• 791        Custom Sort String
• Trapping Rain Water
• 224        224. Basic Calculator
• 227        Basic Calculator II
  

6/8

• 518        coin change2
• 469        Convex Polygon
• 257        Binary Tree Paths: Given a binary tree, return all root-to-leaf paths.
• 124        Given a non-empty binary tree, find the maximum path sum. Doesn't need to go through the root
• 103        Binary Tree Zigzag Level Order Traversal
• 101        Symmetric tree
• 344        Reverse String
• 268        Missing Number: Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array
  

4/11:
Ugly number II
Reverse Words in a String
Permutations II. 太久没写这题 竟然几遍才过。。。

4/12

• Restore IP Addresses
• Wildcard Matchin
• Wiggle Sort
  

中心点 发表于 2019-4-13 13:33
4/12
1. Restore IP Addresses   2. Wildcard Matchin  3. Wiggle Sort

我最近也在刷,我的leetcode好像才刷了几十题.准备开个帖子,共勉.

4/13

• Path sum I, II;
• word search I, II
  

4/14
word search II with Trie

4/15

• Top K Frequent Words： O(n) time
• Populating Next Right Pointers in Each Node: O(1) space
• Binary Tree Paths
• Best Time to Buy and Sell Stock
  

4/16

• Binary Search Tree Iterator 不知道为什么第一感觉是用 queue..
• Add String
• Multiply Strings
• Lowest Common Ancestor of a Binary Search Tree
• Alien Dictionary
  

4/17:

• Merge k Sorted Lists
• Binary Tree Vertical Order Traversal
  

4/18

• Find First and Last Position of Element in Sorted Array
• Serialize and Deserialize Binary Tree
• Continuous Subarray Sum