厉兵秣码

Leetcode - 217 Contains Duplicate (Easy) 题目描述：判断数组中是否存在重复元素。 Input: [1,2,3,1] Output: true public boolean containsDuplicate(int[] nums) { Set<Integer> set = new HashSet<>(); for (...

Leetcode - 36 Valid Sudoku (Medium) 题目描述：给定一个 9 × 9 的不完整数独数组，判定是否合法。 解题思路：判断每一行、每一列和每个 3 × 3 单元格是否有重复的数字。 public boolean isValidSudoku(char[][] board) { boolean[][] row = new boolean[9][9]; bo...

Leetcode - 1 Two Sum (Easy) 题目描述：给定一个数组，返回相加和为 target 的两个元素的下标。 Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1]. public int[] twoSum(int[] nums, int tar...

Leetcode - 3 Longest Substring Without Repeating Characters (Medium) Input: "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. 解题思路：使用 HashMap 记录出现字符的位置，利用双指针滑动窗口记录子串的长度。 ...