diff --git a/ABOUTME.md b/ABOUTME.md new file mode 100644 index 00000000..852c898a --- /dev/null +++ b/ABOUTME.md @@ -0,0 +1,6 @@ +# 关于我 + +【关于自己】：大家好，我是刘剑波，坐标江苏省南通市崇川区，性格内向，希望在算法训练营与优秀的大家一起学习，也希望培养起刻意练习的习惯，持续学习。 +【关于工作】：目前从事Java开发工作，主要负责公司网站群产品的功能升级和大数据产品的落地。 +【工作之外】：平时骑车上班，每天大约20公里，有时候看看书，有时候看看电影，喜欢纪录频道。 +【想跟你分享】：如果给我10分钟，我希望跟同学们分享关于我职业发展中的一些思考。 \ No newline at end of file diff --git a/Week_01/id_38/LeetCode_15_038.java b/Week_01/id_38/LeetCode_15_038.java new file mode 100644 index 00000000..4aac56c0 --- /dev/null +++ b/Week_01/id_38/LeetCode_15_038.java @@ -0,0 +1,50 @@ +import java.util.*; + +/* + * @lc app=leetcode.cn id=15 lang=java + * + * [15] 三数之和 + * 要点1:答案中不包含重复的三元组 + */ +class LeetCode_15_038 { + public List> threeSum(int[] nums) { + if (nums.length < 3) return null; + Arrays.sort(nums); + + List> result = new ArrayList<>(); + + if (nums[0] <= 0 && nums[nums.length - 1] >= 0) { + for (int i = 0; i < nums.length - 2; ++i) { + if (i > 0 && nums[i-1] == nums[i]) continue; + + int l = i +1, r = nums.length - 1; + while(l < r){ + if(nums[r] > -nums[i]-nums[l]){ + while(l < r && nums[r-1] == nums[r]) r--; + r--; + } + else if(nums[r] < -nums[i]-nums[l]){ + while(l < r && nums[l+1] == nums[l]) l++; + l++; + } + else{ + result.add(Arrays.asList(nums[i],nums[l],nums[r])); + while(l < r && nums[r-1] == nums[r]) r--; + while(l < r && nums[l+1] == nums[l]) l++; + r--; + l++; + } + } + } + } + + return result; + } + + public static void main(String[] args) { + LeetCode_15_038 testCode_15_038 = new LeetCode_15_038(); + int[] nums = new int[]{-1,0,1,2,-1,-4}; + System.out.println(testCode_15_038.threeSum(nums)); + } +} + diff --git a/Week_01/id_38/LeetCode_242_038.java b/Week_01/id_38/LeetCode_242_038.java new file mode 100644 index 00000000..80b73725 --- /dev/null +++ b/Week_01/id_38/LeetCode_242_038.java @@ -0,0 +1,30 @@ +/* + * @lc app=leetcode.cn id=242 lang=java + * + * [242] 有效的字母异位词 + * 要点1:答案中不包含重复的三元组 + */ +class LeetCode_242_038 { + + public boolean isAnagram(String s, String t) { + if (s.length() != t.length()) return false; + + int[] hash = new int[26]; + for(int i = 0; i < s.length(); ++i) { + hash[s.charAt(i) - 'a']++; + hash[t.charAt(i) - 'a']--; + } + + for (int i = 0; i < hash.length; ++i) { + if (hash[i] != 0) return false; + } + + return true; + } + + public static void main(String[] args) { + LeetCode_242_038 testCode_242_038 = new LeetCode_242_038(); + System.out.println(testCode_242_038.isAnagram("aaab", "baaa")); + } +} + diff --git a/Week_01/id_38/LeetCode_26_038.java b/Week_01/id_38/LeetCode_26_038.java new file mode 100644 index 00000000..b2b73cf1 --- /dev/null +++ b/Week_01/id_38/LeetCode_26_038.java @@ -0,0 +1,37 @@ +/* + * @lc app=leetcode.cn id=26 lang=java + * + * [26] 删除排序数组中的重复项 + * 要点1:有序数组 + * 要点2:原地删除 + */ +class LeetCode_26_038 { + + /** + * 时间复杂度：O(n) + * 空间复杂度：不需要额外空间 + * @param nums + * @return + */ + public int removeDuplicates(int[] nums) { + // check valid + if (nums.length == 0) return 0; + + // process + int i = 0; + for (int j = 1; j < nums.length; ++j){ + if (nums[i] != nums[j]) { + i++; + nums[i] = nums[j]; + } + } + return i + 1; + } + + public static void main(String[] args) { + LeetCode_26_038 testCode_26_038 = new LeetCode_26_038(); + int[] nums = new int[]{1, 1, 2, 2, 4, 5, 7}; + System.out.println(testCode_26_038.removeDuplicates(nums)); + } +} + diff --git a/Week_01/id_38/LeetCode_50_038.java b/Week_01/id_38/LeetCode_50_038.java new file mode 100644 index 00000000..47e134b0 --- /dev/null +++ b/Week_01/id_38/LeetCode_50_038.java @@ -0,0 +1,24 @@ +/* + * @lc app=leetcode.cn id=50 lang=java + * + * [50] Pow(x, n) + */ +class LeetCode_50_038 { + public double myPow(double x, int n) { + if (n == 0) return 1.0; + + double half = myPow(x, n / 2); + if (n % 2 == 0) { + return half * half; + } else { + return half * half * x; + } + + } + + public static void main(String[] args) { + LeetCode_50_038 testCode_50_038 = new LeetCode_50_038(); + System.out.println(testCode_50_038.myPow(2, 10)); + } +} + diff --git a/Week_01/id_38/README.md b/Week_01/id_38/README.md new file mode 100644 index 00000000..b11159e4 --- /dev/null +++ b/Week_01/id_38/README.md @@ -0,0 +1,65 @@ +# 学习笔记 + +## 第一周题目 +--- +### 数组、链表 +【简单】[26. 删除排序数组中的重复项 ](https://leetcode-cn.com/problems/remove-duplicates-from-sorted-array/) + +【简单】[189. 旋转数组](https://leetcode-cn.com/problems/rotate-array/) + +【简单】[21. 合并两个有序链表](https://leetcode-cn.com/problems/merge-two-sorted-lists/) + +【简单】[88. 合并两个有序数组](https://leetcode-cn.com/problems/merge-sorted-array/) + +【中等】[24. 两两交换链表中的节点](https://leetcode-cn.com/problems/swap-nodes-in-pairs/) + +【中等】[15. 三数之和](https://leetcode-cn.com/problems/3sum/) + +--- + +### Map & Set +[242. 有效的字母异位词【简单】](https://leetcode-cn.com/problems/valid-anagram/) + +[49. 字母异位词分组【中等】](https://leetcode-cn.com/problems/group-anagrams/) + +--- + +### 堆栈、队列 + +[1047. 删除字符串中的所有相邻重复项【简单】](https://leetcode-cn.com/problems/remove-all-adjacent-duplicates-in-string/) + +[1021. 删除最外层的括号【简单】](https://leetcode-cn.com/problems/remove-outermost-parentheses/) + +[84. 柱状图中最大的矩形【困难】](https://leetcode.com/problems/largest-rectangle-in-histogram/) + +[42. 接雨水【困难】](https://leetcode.com/problems/trapping-rain-water/) + +--- + +### 二分查找 + +[441. 排列硬币【简单】](https://leetcode-cn.com/problems/arranging-coins/) + +[50. Pow(x, n)【中等】](https://leetcode-cn.com/problems/powx-n/) + +[174. 地下城游戏【困难】](https://leetcode-cn.com/problems/dungeon-game/) + + +--- + +### 递归 + +[104. 二叉树的最大深度【简单】](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/) + +[101. 对称二叉树【简单】](https://leetcode-cn.com/problems/symmetric-tree/) + +[111. 二叉树的最小深度【简单】](https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/) + +[783. 二叉搜索树结点最小距离【简单】](https://leetcode-cn.com/problems/minimum-distance-between-bst-nodes/) + +[257. 二叉树的所有路径【简单】](https://leetcode-cn.com/problems/binary-tree-paths/) + +[938. 二叉搜索树的范围和【简单】](https://leetcode-cn.com/problems/range-sum-of-bst/) + +[236. 二叉树的最近公共祖先【中等】](https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree/) + diff --git "a/Week_01/id_38/\346\225\260\346\215\256\347\273\223\346\236\204\344\270\216\347\256\227\346\263\225\346\200\273\347\273\223.xmind" "b/Week_01/id_38/\346\225\260\346\215\256\347\273\223\346\236\204\344\270\216\347\256\227\346\263\225\346\200\273\347\273\223.xmind" new file mode 100644 index 00000000..13ad0407 Binary files /dev/null and "b/Week_01/id_38/\346\225\260\346\215\256\347\273\223\346\236\204\344\270\216\347\256\227\346\263\225\346\200\273\347\273\223.xmind" differ