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Posts published in “Binary Search”

花花酱 LeetCode 744. Find Smallest Letter Greater Than Target

Problem:

Given a list of sorted characters letters containing only lowercase letters, and given a target letter target, find the smallest element in the list that is larger than the given target.

Letters also wrap around. For example, if the target is target = 'z' and letters = ['a', 'b'], the answer is 'a'.

Examples:

Note:

  1. letters has a length in range [2, 10000].
  2. letters consists of lowercase letters, and contains at least 2 unique letters.
  3. target is a lowercase letter.

Link: https://leetcode.com/problems/find-smallest-letter-greater-than-target/description/ 

Idea:

  1. Scan the array Time complexity: O(n)
  2. Binary search Time complexity: O(logn)

Solution 1:

C++ / Scan

C++ / Set

C++ / Binary Search

 

花花酱 LeetCode 729. My Calendar I

Problem:

Implement a MyCalendar class to store your events. A new event can be added if adding the event will not cause a double booking.

Your class will have the method, book(int start, int end). Formally, this represents a booking on the half open interval [start, end), the range of real numbers x such that start <= x < end.

double booking happens when two events have some non-empty intersection (ie., there is some time that is common to both events.)

For each call to the method MyCalendar.book, return true if the event can be added to the calendar successfully without causing a double booking. Otherwise, return false and do not add the event to the calendar.

Your class will be called like this: MyCalendar cal = new MyCalendar(); MyCalendar.book(start, end)

Example 1:

Note:

 

  • The number of calls to MyCalendar.book per test case will be at most 1000.
  • In calls to MyCalendar.book(start, end)start and end are integers in the range [0, 10^9].

 



Idea: 

Binary Search

Solution1:

Brute Force: O(n^2)

C++

Solution 2:

Binary Search O(nlogn)

C++

Java

 

Related Problems:

花花酱 LeetCode 4. Median of Two Sorted Arrays

题目大意:求两个已经排序的数组的中位数(如果合并后)。

Problem:

There are two sorted arrays nums1 and nums2 of size m and n respectively.

Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).

Example 1:

Example 2:



Idea:

Binary Search

Time complexity: O(log(min(n1,n2)))

Space complexity: O(1)

 

Solution: Binary Search

C++

Java

Related Problem:

花花酱 LeetCode 719. Find K-th Smallest Pair Distance

题目大意:给你一个数组,返回所有数对中,绝对值差第k小的值。

Problem:

Given an integer array, return the k-th smallest distance among all the pairs. The distance of a pair (A, B) is defined as the absolute difference between A and B.

Example 1:

Note:

  1. 2 <= len(nums) <= 10000.
  2. 0 <= nums[i] < 1000000.
  3. 1 <= k <= len(nums) * (len(nums) - 1) / 2.

Idea

Bucket sort

Binary search / dp

Solution

C++ / binary search

 

C++ / bucket sort w/ vector O(n^2)

Related Problems: