2022 年 3月随笔档案 - 阳光明媚的菲越

641. Design Circular Deque

摘要：My first solution - using ArrayList: class MyCircularDeque { List<Integer> list = new ArrayList<>(); int k ; public MyCircularDeque(int k) { this.k = 阅读全文

posted @ 2022-03-31 06:49 阳光明媚的菲越阅读(27) 评论(0) 推荐(0)

66. Plus One

摘要：My first solution: class Solution { public int[] plusOne(int[] digits) { int n = digits.length; int carry = 1; for(int i=n-1;i>=0;i--){ int digit = di 阅读全文

posted @ 2022-03-31 04:13 阳光明媚的菲越阅读(282) 评论(0) 推荐(0)

69. Sqrt(x)

摘要：Using binary search, time complexity: O(log(x)) class Solution { public int mySqrt(int x) { int l=1, r =x; while(l<r-1){ int mid=l+(r-l)/2; int temp = 阅读全文

posted @ 2022-03-31 01:01 阳光明媚的菲越阅读(36) 评论(0) 推荐(0)

772. Basic Calculator III

摘要：class Solution { public int calculate(String s) { s = s.replace(" ", "")+'+'; //Add a '+' or '-' is necessary, otherwise, the case (1+1) will return 0 阅读全文

posted @ 2022-03-29 14:03 阳光明媚的菲越阅读(41) 评论(0) 推荐(0)

224. Basic Calculator

摘要：这道题跟227题，背下来！ Iterative: class Solution { public int calculate(String s) { s=s.replace(" ", "")+'+'; Stack<Integer> stk = new Stack<>(); int sign =1; 阅读全文

posted @ 2022-03-29 13:12 阳光明媚的菲越阅读(31) 评论(0) 推荐(0)

875. Koko Eating Bananas

摘要：Using Binary Search Template: class Solution { public int minEatingSpeed(int[] piles, int h) { int l=1, r=0; for(int i=0;i<piles.length;i++){ r = Math 阅读全文

posted @ 2022-03-24 05:47 阳光明媚的菲越阅读(27) 评论(0) 推荐(0)

926. Flip String to Monotone Increasing

摘要：class Solution { public int minFlipsMonoIncr(String s) { int oneNum = 0, flipNum =0; int res =0; for(char c: s.toCharArray()){ if(c=='0'){ if(oneNum== 阅读全文

posted @ 2022-03-22 06:09 阳光明媚的菲越阅读(23) 评论(0) 推荐(0)

2104. Sum of Subarray Ranges

摘要：By adding a 'max' and 'min' variable, we can make the solution's time complexity from O(n3) to O(n2): public long subArrayRanges(int[] nums) { long re 阅读全文

posted @ 2022-03-22 05:19 阳光明媚的菲越阅读(40) 评论(0) 推荐(0)

1710. Maximum Units on a Truck

摘要：Solution 1, Using a PriorityQueue class Solution { public int maximumUnits(int[][] boxTypes, int truckSize) { PriorityQueue<int[]> queue = new Priorit 阅读全文

posted @ 2022-03-22 03:53 阳光明媚的菲越阅读(25) 评论(0) 推荐(0)

1268. Search Suggestions System

摘要：I user Trie to store the products. For every Trie node, it has the links to the next character and a PriorityQueue. The PriorityQueue is used to store 阅读全文

posted @ 2022-03-19 06:46 阳光明媚的菲越阅读(21) 评论(0) 推荐(0)

937. Reorder Data in Log Files

摘要：This is a problem which check whether you know how to user Arrays.sort(). Time complexity: O(n*log(n)) Solution 1: Using comparator class Solution { p 阅读全文

posted @ 2022-03-19 03:39 阳光明媚的菲越阅读(38) 评论(0) 推荐(0)

2096. Step-By-Step Directions From a Binary Tree Node to Another

摘要：My first solution: 1. find lowest common ancestor of start and dest. 2. find path's length from LCA to start 3. find path from LCA to dest. 4. Combine 阅读全文

posted @ 2022-03-12 11:05 阳光明媚的菲越阅读(87) 评论(0) 推荐(0)

1146. Snapshot Array

摘要：The following is my first solution, very easy to understand, but brute force: For every snapshot, we clone the whole array. Time complexity of snap(): 阅读全文

posted @ 2022-03-11 05:32 阳光明媚的菲越阅读(50) 评论(0) 推荐(0)

366. Find Leaves of Binary Tree

摘要：Instead of counting levels form root to leaves, this problem is counting levels from leaves to root. That is the leaves has the height of 1, and the r 阅读全文

posted @ 2022-03-11 04:13 阳光明媚的菲越阅读(14) 评论(0) 推荐(0)

766. Toeplitz Matrix

摘要：The most simple version: class Solution { public boolean isToeplitzMatrix(int[][] matrix) { if(matrix==null||matrix[0].length==0) return true; int m = 阅读全文

posted @ 2022-03-10 01:45 阳光明媚的菲越阅读(23) 评论(0) 推荐(0)

498. Diagonal Traverse

摘要：This is a hard problem. If I got this problem the first time when I was interviewed, I would not be able to solve it. public int[] findDiagonalOrder(i 阅读全文

posted @ 2022-03-09 14:23 阳光明媚的菲越阅读(25) 评论(0) 推荐(0)

317. Shortest Distance from All Buildings

摘要：This problem is different with 542. 01 Matrix and 286. Walls and Gates. 542 and 286 is once get the shortest path from one of the targets, then the ce 阅读全文

posted @ 2022-03-09 11:50 阳光明媚的菲越阅读(44) 评论(0) 推荐(0)

286. Walls and Gates

摘要：The solution of this issue is as same as 542. 01 Matrix class Solution { int m, n; private int[][] dirs ={{-1,0},{1,0},{0,-1},{0,1}}; public void wall 阅读全文

posted @ 2022-03-09 05:18 阳光明媚的菲越阅读(35) 评论(0) 推荐(0)

48. Rotate Image

摘要：If you could find the secret of image rotate, then this would be a simple problem. 1. If you want to rotate the image by 90 degrees clockwise，then rev 阅读全文

posted @ 2022-03-09 03:57 阳光明媚的菲越阅读(34) 评论(0) 推荐(0)

212. Word Search II

摘要：This problem need to solve mutiple Strings, so we use a Trie to store all strings, and then do DFS. Time complexity: O(m*n*3L), L is the maximum of th 阅读全文

posted @ 2022-03-08 15:28 阳光明媚的菲越阅读(40) 评论(0) 推荐(0)

79. Word Search

摘要：Although this is a matrix problem, but it cannot be done by BFS, following is my solution, but it doesn't work when the test case is: [["A","B","C","E 阅读全文

posted @ 2022-03-08 12:56 阳光明媚的菲越阅读(50) 评论(0) 推荐(0)

200. Number of Islands

摘要：If you know how to solve 827. Making A Large Island, then this one is a piece of cake: class Solution { private int res =0; int m,n; public int numIsl 阅读全文

posted @ 2022-03-08 08:33 阳光明媚的菲越阅读(34) 评论(0) 推荐(0)

827. Making A Large Island

摘要：This problem is based on 695. Max Area of Island 1. Create a islands matrix, if a cell in grid is 1, there will be a corresponding island number in is 阅读全文

posted @ 2022-03-08 08:16 阳光明媚的菲越阅读(38) 评论(0) 推荐(0)

542. 01 Matrix

该文被密码保护。

posted @ 2022-03-08 05:17 阳光明媚的菲越阅读(0) 评论(0) 推荐(0)

1730. Shortest Path to Get Food

摘要：This is a easier common grap and look for shortest path problem, time complexity: O(m*n): class Solution { public int getFood(char[][] grid) { int m = 阅读全文

posted @ 2022-03-05 15:02 阳光明媚的菲越阅读(33) 评论(0) 推荐(0)

1293. Shortest Path in a Grid with Obstacles Elimination

摘要：This is graph and look for the shortest path, so BFS should be solution. But how to handle K? We can look K as a parameter of every node. My first sol 阅读全文

posted @ 2022-03-05 14:29 阳光明媚的菲越阅读(53) 评论(0) 推荐(0)

1197. Minimum Knight Moves

摘要：This is a graph problem, and the problem try to find the shortest path. So BFS is just right solution, the following is my first solution. It works bu 阅读全文

posted @ 2022-03-05 09:03 阳光明媚的菲越阅读(51) 评论(0) 推荐(0)