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quicksort是一个comparison-based的排序算法（heap sort，merge sort，插入都是） 阅读全文
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import java.util.* import kotlin.collections.HashMap /** * 1161. Maximum Level Sum of a Binary Tree * https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree/description/ * */ class Tree... 阅读全文
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package LeetCode_3 import java.lang.StringBuilder /** * 3. Longest Substring Without Repeating Characters * https://leetcode.com/problems/longest-subs 阅读全文
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/** * 905. Sort Array By Parity * https://leetcode.com/problems/sort-array-by-parity/description/ * * Given an array A of non-negative integers, return an array consisting of all the even elements of 阅读全文
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/** 48. Rotate Image https://leetcode.com/problems/rotate-image/description/ */ class Solution { public void rotate(int[][] matrix) { //N x N matrix have floor(N/2) square cycers, for example 4x4 matr 阅读全文
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在ubuntu系统下，更新android studio 3.5时，提示 jre/bin/java没写权限，发现解决方法如下： https://askubuntu.com/questions/1083125/android-studio-update-issue-with-jre-bin-java 阅读全文
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/** * 700. Search in a Binary Search Tree * https://leetcode.com/problems/search-in-a-binary-search-tree/description/ * */ class TreeNode(var `val`: Int) { var left: TreeNode? = null var ... 阅读全文
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958. Check Completeness of a Binary Tree //https://leetcode.com/problems/check-completeness-of-a-binary-tree/description/ class TreeNode(var `val`: Int) { var left: TreeNode? = null var right: TreeNod 阅读全文
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class MinHeap constructor(maxSize_: Int) { var size = 0 var maxSize = maxSize_ var heapArray: Array? = null companion object { const val FRONT = 1 ... 阅读全文
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/** * This problem was asked by Microsoft. Given an array of numbers and a number k, determine if there are three entries in the array which add up to the specified number k. For example, given [20... 阅读全文