Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique.
Example 1:
Input: arr = [1,2,2,1,1,3]
Output: true
Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.
Write a program that outputs the string representation of numbers from 1 to n, however:
If the number is divisible by 3, output “fizz”.
If the number is divisible by 5, output “buzz”.
If the number is divisible by both 3 and 5, output “fizzbuzz”.
For example, for n = 15, we output: 1, 2, fizz, 4, buzz, fizz, 7, 8, fizz, buzz, 11, fizz, 13, 14, fizzbuzz.
Suppose you are given the following code:
class FizzBuzz {
public FizzBuzz(int n) { ... } // constructor
public void fizz(printFizz) { ... } // only output "fizz"
public void buzz(printBuzz) { ... } // only output "buzz"
public void fizzbuzz(printFizzBuzz) { ... } // only output "fizzbuzz"
public void number(printNumber) { ... } // only output the numbers
}
Implement a multithreaded version of FizzBuzz with four threads. The same instance of FizzBuzz will be passed to four different threads:
Thread A will call fizz() to check for divisibility of 3 and outputs fizz.
Thread B will call buzz() to check for divisibility of 5 and outputs buzz.
Thread C will call fizzbuzz() to check for divisibility of 3 and 5 and outputs fizzbuzz.
Thread D will call number() which should only output the numbers.
You are given a string s, and an array of pairs of indices in the string pairs where pairs[i] = [a, b] indicates 2 indices(0-indexed) of the string.
You can swap the characters at any pair of indices in the given pairsany number of times.
Return the lexicographically smallest string that s can be changed to after using the swaps.
Example 1:
Input: s = "dcab", pairs = [[0,3],[1,2]]
Output: "bacd"
Explaination:
Swap s[0] and s[3], s = "bcad"
Swap s[1] and s[2], s = "bacd"
Example 2:
Input: s = "dcab", pairs = [[0,3],[1,2],[0,2]]
Output: "abcd"
Explaination:
Swap s[0] and s[3], s = "bcad"
Swap s[0] and s[2], s = "acbd"
Swap s[1] and s[2], s = "abcd"
Example 3:
Input: s = "cba", pairs = [[0,1],[1,2]]
Output: "abc"
Explaination:
Swap s[0] and s[1], s = "bca"
Swap s[1] and s[2], s = "bac"
Swap s[0] and s[1], s = "abc"
Constraints:
1 <= s.length <= 10^5
0 <= pairs.length <= 10^5
0 <= pairs[i][0], pairs[i][1] < s.length
s only contains lower case English letters.
Solution: Connected Components
Use DFS / Union-Find to find all the connected components of swapable indices. For each connected components (index group), extract the subsequence of corresponding chars as a string, sort it and put it back to the original string in the same location.
e.g. s = “dcab”, pairs = [[0,3],[1,2]] There are two connected components: {0,3}, {1,2} subsequences: 1. 0,3 “db”, sorted: “bd” 2. 1,2 “ca”, sorted: “ac” 0 => b 1 => a 2 => c 3 => d final = “bacd”
Time complexity: DFS: O(nlogn + k*(V+E)), Union-Find: O(nlogn + V+E) Space complexity: O(n)
Given an array of distinct integers arr, find all pairs of elements with the minimum absolute difference of any two elements.
Return a list of pairs in ascending order(with respect to pairs), each pair [a, b] follows
a, b are from arr
a < b
b - a equals to the minimum absolute difference of any two elements in arr
Example 1:
Input: arr = [4,2,1,3]
Output: [[1,2],[2,3],[3,4]]
Explanation: The minimum absolute difference is 1. List all pairs with difference equal to 1 in ascending order.
