Link : https://leetcode.com/problems/reorder-data-in-log-files/ Problem : You are given an array of logs. Each log is a space-delimited string of words, where the first word is the identifier. There are two types of logs: Letter-logs: All words (except the identifier) consist of lowercase English letters. Digit-logs: All words (except the identifier)…

Link : https://leetcode.com/problems/find-the-duplicate-number/ Problem : Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive. There is only one repeated number in nums, return this repeated number. You must solve the problem without modifying the array nums and uses…

Link : https://leetcode.com/problems/longest-consecutive-sequence/ Problem : Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence. You must write an algorithm that runs in O(n) time. Thoughts : 1. 先把 nums 放進去 set中，排除重複的數字。 2. 跑 nums迴圈，假設 nums-1 數字有在 set 中，那 nums 就不能當開頭。 3. 如果 nums-1沒有在 set 中，那就可以當開頭，計算值為1，如果 nums+1有在…

Link : https://leetcode.com/problems/increasing-triplet-subsequence/ Problem: Given an integer array nums, return true if there exists a triple of indices (i, j, k) such that i < j < k and nums[i] < nums[j] < nums[k]. If no such indices exists, return false. Thoughts： 1. 直接跑array內的值(nums[i] < nums[j] < nums[k])做比較，i<j<k這個照迴圈跑就可以達成。 2. first, second先設為 infinity，然後比較小的值取代掉…

Link :https://leetcode.com/problems/container-with-most-water/ Problem : Given n non-negative integers a1, a2, ..., an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of the line i is at (i, ai) and (i, 0). Find two lines, which, together with the…

Link : https://leetcode.com/problems/jump-game/ Problem : Given an array of non-negative integers nums, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Determine if you are able to reach the last index. 有一個array nums，起始位置在 first index，每一次前進的值為nums[i]，試問是否在array結束前來到最後最後一個數上。 …

Link : https://leetcode.com/problems/employee-importance/ Problem : You have a data structure of employee information, which includes the employee’s unique id, their importance value, and their direct subordinates’ id. You are given an array of employees employees where: employees[i].id is the ID of the ith employee. employees[i].importance is the importance value of…

Link : https://leetcode.com/problems/pascals-triangle-ii/ Problem : Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal's triangle. In Pascal’s trian …

Link : https://leetcode.com/problems/pascals-triangle/ Problem : Given an integer numRows, return the first numRows of Pascal's triangle.