set | 易学教程

Whats the best algorithm for Non Disjoint Set Union?

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问题 Lets say there are two (non disjoint) sets of points (cartesian space), what is the best case complexity algorithm to perform the union of the two sets ? 回答1: Since the point coordinates are arbitrary and there is no special relation between them, I don't see this problem as a geometric specific problem. It is the generic problem of efficiently merging S1 and S2 into a new set S. I know about two options: 1) When the sets are stored in a hash table (actually a hash set), the union takes O(|S1

Whats the best algorithm for Non Disjoint Set Union?

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Numbers of common distinct difference

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问题 Given two array A and B. Task to find the number of common distinct (difference of elements in two arrays). Example : A=[3,6,8] B=[1,6,10] so we get differenceSet for A differenceSetA=[abs(3-6),abs(6-8),abs(8-3)]=[3,5,2] similiarly differenceSetB=[abs(1-6),abs(1-10),abs(6-10)]=[5,9,4] Number of common elements=Intersection :{differenceSetA,differenceSetB}={5} Answer= 1 My approach O(N^2) int commonDifference(vector<int> A,vector<int> B){ int n=A.size(); int m=B.size(); unordered_set<int>

intersection of three sets in python?

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问题 Currently I am stuck trying to find the intersection of three sets. Now these sets are really lists that I am converting into sets, and then trying to find the intersection of. Here's what I have so far: for list1 in masterlist: list1 = thingList1 for list2 in masterlist: list2 = thingList2 for list3 in masterlist: list3 = thingList3 d3 = [set(thingList1), set(thingList2), set(thingList3)] setmatches c = set.intersection(*map(set,d3)) print setmatches and I'm getting set([]) Script terminated

how can I maintain sequence of my list using set?

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问题 In [1]: l1 = ['a',2,3,0,9.0,0,2,6,'b','a'] In [2]: l2 = list(set(l1)) In [3]: l2 Out[3]: ['a', 0, 2, 3, 6, 9.0, 'b'] Here you can see the the list l2 is falling with different sequence then the original l1, I need to remove the duplicate elements from my list without changing the sequence/order of the list elements.... 回答1: If you are not concerned with efficiency, this is O(n*m) >>> sorted(set(l1), key=l1.index) ['a', 2, 3, 0, 9.0, 6, 'b'] Using an intermediate dict is more complicated, but

【SICP练习】87 练习2.59

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练习2.59 我们可以采用迭代来完成这个过程，至于怎么迭代的，接下来就是代码了。 ( define ( union-set set1 set2) ( define ( union-set-iter set1 set2) ( if ( null? input) ( reverse result) ( let ( ( current-element ( car input) ) ( remain-element ( cdr input) ) ( if ( element-of-set? current-element result) ( union-set-iter remain-element result) ( union-set-iter remain-element ( cons current-element result) ) ) ) ) ) ( union-set-iter ( append set1 set2) ‘ () ) ) 感谢访问，希望对您有所帮助。欢迎关注或收藏、评论或点赞。为使本文得到斧正和提问，转载请注明出处： http://blog.csdn.net/nomasp 版权声明：本文为 NoMasp柯于旺原创文章，未经许可严禁转载！欢迎访问我的博客：http://blog.csdn.net/nomasp 来源： oschina 链接： https:/

setting a local bash variable from an ssh command

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问题 I am running a chain of sshpass > ssh > commands, I would like to store the exit code of one of those commands ran in the remote server in a variable so I can access it back in the local after ssh is done. What I have done so far does not seem to store anything. Help please! My Code: sshpass -p password ssh user@ip "echo \"first command\" ; su -lc \"./root_script.sh\" ; set MYVAR = $? ; rm root_script.sh \" if (( $MYVAR != 0 )) ; then echo "Cannot continue program without root password" exit

Get a set of 2d list in python

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问题 I have a list like follows t=[[1, 7], [3, 7], [1, 7], [5, 8], [3, 7]] I need to get a set out of this so the output would be like t=[[1, 7], [3, 7], [5, 8]] I tried to use t=set(t) but it didn't work 回答1: If you do not care about the order, you can first convert the inner lists to tuples using map() function, and then convert them to set and then back to list . Example - >>> t=[[1, 7], [3, 7], [1, 7], [5, 8], [3, 7]] >>> t = list(set(map(tuple,t))) >>> t [(3, 7), (5, 8), (1, 7)] 回答2: The

How do I change a certain value in a matrix in Haskell?

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问题 I'm very new to Haskell and haven't fully understood how it works yet. In the following method I would like to change a certain value in a matrix or as it is realized in Haskell, a list of lists. setEntry :: [[Int]] -> Int -> Int -> Int -> [[Int]] setEntry x i j aij = This is my method so far. I know it's not much but I really don't know how to continue. The plan is to give it a matrix and then change the value that can be found in the ith line and the jth column to aij. I'd be very grateful

Getting first member of a BTreeSet

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问题 In Rust, I have a BTreeSet that I'm using to keep my values in order. I have a loop that should retrieve and remove the first (lowest) member of the set. I'm using a cloned iterator to retrieve the first member. Here's the code: use std::collections::BTreeSet; fn main() { let mut start_nodes = BTreeSet::new(); // add items to the set while !start_nodes.is_empty() { let mut start_iter = start_nodes.iter(); let mut start_iter_cloned = start_iter.cloned(); let n = start_iter_cloned.next().unwrap