原创 leetcode 217: Contains Duplicate
class Solution { public: bool containsDuplicate(vector<int>& nums) { unordered_set<int> set; int n=
2020-02-22 14:17:32
原创 leetcode 216: Combination Sum III
class Solution { public: vector<vector<int>> combinationSum3(int k, int n) { vector<vector<int> > res;
2020-02-22 14:17:32
原创 leetcode 229: Majority Element
Extended from Majority Element. Now there are at most two majority element, so I need four variables to implement the m
2020-02-22 14:17:32
原创 leetcode 233: Number of Digit One
This problem is a little hard to understand. You can write some numbers and calculate the number of Digit Ones by hand
2020-02-22 14:17:32
原创 leetcode 214: Shortest Palindrome
Use KMP algorithm. First, get the reverse of the string s called new_s, and add s, a special character ('#') and new_s
2020-02-22 14:17:32
原创 leetcode 3: Longest Substring Without Repeating Characters
Use a window to get a substring. The end of the window keeps forward and once it meets a character that is already in t
2018-08-31 04:46:26
原创 leetcode 109: Convert Sorted List to Binary Search Tree
Use the fast slow method to find the mid point of the list and make it the root. Then do it recursively on both sides.
2018-08-31 04:46:26
3
原创 leetcode 6: ZigZag Conversion
In one line, the first character is s[i], the second is s[i+2*numRows-2-2*i] and the third is s[i+2*numRows-2]. Just be
2018-08-31 04:46:24
2
原创 leetcode 5: Longest Palindrome Substring
Use DP. dp[i][j] means whether the substring i to j is a palindrome. class Solution { public: string longestPalind
2018-08-31 04:46:24
原创 leetcode 1: Two Sum
Use a unordered map to save all visited number. While scan the array, find out whether target-nums[i] is already visite
2018-08-31 04:46:24
原创 leetcode 8: Sting to Integer (atoi)
class Solution { public: int myAtoi(string str) { int len=str.length(); int i=0; while(i<le
2018-08-31 04:46:24
3
原创 leetcode 9: Palindrome Number
Reverse the number and compare it with the original one. class Solution { public: bool isPalindrome(int x) {
2018-08-31 04:46:24
原创 leetcode 321: Create Maximum Number
The algorithm is quite difficult, you need to think step by step to come up with the idea. I learned the algorithm here
2018-08-31 04:46:23
2
原创 leetcode 241: Different Ways to Add Parentheses
Learn from https://leetcode.com/discuss/48488/c-4ms-recursive-%26-dp-solution-with-brief-explanation. Recursion method,
2018-08-31 04:46:23
原创 leetcode 237: Delete Node in a Linked List
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(i
2018-08-31 04:46:23
4