Given a collection of intervals, merge all overlapping intervals.
Example 1:
Input: [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6].Example 2:
Input: [[1,4],[4,5]] Output: [[1,5]] Explanation: Intervals [1,4] and [4,5] are considerred overlapping.
合并区间重叠/相邻的区间。
Given an array of non-negative integers, 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.
Example 1:
Input: [2,3,1,1,4] Output: true Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.Example 2:
Input: [3,2,1,0,4] Output: false Explanation: You will always arrive at index 3 no matter what. Its maximum jump length is 0, which makes it impossible to reach the last index.
给定一个非负整型数组，每个数字表示可以从该位置向后跳跃的最大步数。
判断是否能从第一个数字开始跳跃到最后一个数字。
Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
Example 1:
Input: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] Output: [1,2,3,6,9,8,7,4,5]Example 2:
Input: [ [1, 2, 3, 4], [5, 6, 7, 8], [9,10,11,12] ] Output: [1,2,3,4,8,12,11,10,9,5,6,7]
从外向内螺旋形遍历矩阵。
A robot is located at the top-left corner of a m x n grid (marked ‘Start’ in the diagram below).
The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked ‘Finish’ in the diagram below).
How many possible unique paths are there?
Given an unsorted integer array, find the smallest missing positive integer.
Example 1:
Input: [1,2,0] Output: 3Example 2:
Input: [3,4,-1,1] Output: 2Example 3:
Input: [7,8,9,11,12] Output: 1Note:
- Your algorithm should run in O(n) time and uses constant extra space.
使用O(n)的时间复杂度和O(1)的空间在无序数组中查找第一个缺失的正数。
Given a collection of candidate numbers (
candidates) and a target number (target), find all unique combinations in candidates where thecandidatenumbers sums totarget.Each number in
candidatesmay only be used once in the combination.Note:
All numbers (including
target) will be positive integers. The solution set must not contain duplicate combinations.
Given a set of candidate numbers (
candidates) (without duplicates) and a target number (target), find all unique combinations incandidateswhere the candidate numbers sums totarget.The same repeated number may be chosen from candidates unlimited number of times.
Note:
- All numbers (including
target) will be positive integers.- The solution set must not contain duplicate combinations.
Search in Rotated Sorted Array
Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.
(i.e.,
[0,1,2,4,5,6,7]might become[4,5,6,7,0,1,2]).You are given a target value to search. If found in the array return its index, otherwise return
-1.You may assume no duplicate exists in the array.
Your algorithm’s runtime complexity must be in the order of
O(log n).
