osigmao的专栏

注意跳过重复的元素！//时间复杂度： O(n^2)public class Solution { public List> threeSum(int[] num) { List> res = new ArrayList<>(); if(num == null || num.length < 3) return res; Arra

public class Solution { public List> fourSum(int[] num, int target) { List> res = new ArrayList<>(); if (num == null || num.length < 4) { return res; }

array的找规律的题public class Solution { public int trap(int[] A) { int sum = 0; int maxInd = -1; int max = -1; //find the highest bars; for (int i = 0; i < A.leng

public class Solution { public List> combinationSum(int[] candidates, int target) { if (candidates == null || candidates.length == 0) { return null; } Arrays.so

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the total sum