disjoint-union | 易学教程

How to properly implement disjoint set data structure for finding spanning forests in Python?

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问题 Recently, I was trying to implement the solutions of google kickstater's 2019 programming questions and tried to implement Round E's Cherries Mesh by following the analysis explanation. Here is the link to the question and the analysis. https://codingcompetitions.withgoogle.com/kickstart/round/0000000000050edb/0000000000170721 Here is the code I implemented: t = int(input()) for k in range(1,t+1): n, q = map(int,input().split()) se = list() for _ in range(q): a,b = map(int,input().split()) se

fastest way to merge duplicate cells in without looping Excel

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问题 I have cells containing duplicate values that i want to merge quickly. The table looks like this: Sub MergeCells() Application.DisplayAlerts = False Dim n As Name Dim fc As FormatCondition Dim Rng As Range, R As Range Dim lRow As Long Dim I&, J& Dim arr As Variant ReDim arr(1 To 1) As Variant With ThisWorkbook.Sheets("tst") Set Rng = .Range("A2:D11") lRow = Rng.End(xlDown).Row For J = 1 To 4 For I = lRow To 2 Step -1 'last row to 2nd row If Trim(UCase(.Cells(I, J))) = Trim(UCase(.Cells(I - 1,

Maximum edge weight from one node A to node B

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问题 Given a connected undirected graph having N nodes (1 <= N <= 2 * 10^5) and N-1 edges. Let's define a function F(a,b) , where F(a, b) is equal to the maximum edge weight in the path from a to b . How do we find the sum of the F(a, b) for all a , b such that 1 <= a , b <= N (mod 10^9 + 7) Example figure F(a, b) is equal to the maximum edge weight in the path from a to b. F(1, 2) = 2 F(1, 3) = 2 F(1, 4) = 4 F(1, 5) = 4 F(2, 3) = 1 F(2, 4) = 4 F(2, 5) = 4 F(3, 4) = 4 F(3, 5) = 4 F(4, 5) = 3 Sum

mysql SELECT NOT IN () — disjoint set?

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问题 I'm having a problem getting a query to work, which I think should work. It's in the form SELECT DISTINCT a, b, c FROM t1 WHERE NOT IN ( SELECT DISTINCT a,b,c FROM t2 ) AS alias But mysql chokes where "IN (" starts. Does mysql support this syntax? If not, how can I go about getting these results? I want to find distinct tuples of (a,b,c) in table 1 that don't exist in table 2. 回答1: You should use not exists: SELECT DISTINCT a, b, c FROM t1 WHERE NOT EXISTS (SELECT NULL FROM t2 WHERE t1.a = t2

mysql SELECT NOT IN () — disjoint set?

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I'm having a problem getting a query to work, which I think should work. It's in the form SELECT DISTINCT a, b, c FROM t1 WHERE NOT IN ( SELECT DISTINCT a,b,c FROM t2 ) AS alias But mysql chokes where "IN (" starts. Does mysql support this syntax? If not, how can I go about getting these results? I want to find distinct tuples of (a,b,c) in table 1 that don't exist in table 2. You should use not exists: SELECT DISTINCT a, b, c FROM t1 WHERE NOT EXISTS (SELECT NULL FROM t2 WHERE t1.a = t2.a AND t1.b = t2.b AND t1.c = t2.c) Using NOT IN is not the best method to do this, even if you check only

Disjoint Union in LINQ

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I have two sets (ILists) where I need all the items from the 1st list, where the item is not in the second list. Can anyone point me to the best way of achieving this with a LINQ statement? How about the Except method: var firstMinusSecond = first.Except(second); 来源： https://stackoverflow.com/questions/801757/disjoint-union-in-linq

Disjoint Union in LINQ

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问题 I have two sets (ILists) where I need all the items from the 1st list, where the item is not in the second list. Can anyone point me to the best way of achieving this with a LINQ statement? 回答1: How about the Except method: var firstMinusSecond = first.Except(second); 来源： https://stackoverflow.com/questions/801757/disjoint-union-in-linq