constraints

问题 I have a programming problem (https://blog.svpino.com/2015/05/08/solution-to-problem-5-and-some-other-thoughts-about-this-type-of-questions): Write a program that outputs all possibilities to put + or - or nothing between the numbers 1, 2, ..., 9 (in this order) such that the result is always 100. E.g.: 1 + 2 + 34 – 5 + 67 – 8 + 9 = 100. I solved this problem with Python to get 11 answers : import itertools for operator in [p for p in itertools.product(['+','-',''], repeat=8)]: values = zip(

问题 I have a programming problem (https://blog.svpino.com/2015/05/08/solution-to-problem-5-and-some-other-thoughts-about-this-type-of-questions): Write a program that outputs all possibilities to put + or - or nothing between the numbers 1, 2, ..., 9 (in this order) such that the result is always 100. E.g.: 1 + 2 + 34 – 5 + 67 – 8 + 9 = 100. I solved this problem with Python to get 11 answers : import itertools for operator in [p for p in itertools.product(['+','-',''], repeat=8)]: values = zip(

问题 I've seen this sort of problems a few times and am trying to decide the best way of storing ranges in a non-overlapping manner. For example, when scheduling some sort of resource that only one person can use at a time. Mostly what I've seen is something like this: PERSON ROOM START_TIME END_TIME Col. Mustard Library 08:00 10:00 Prof. Plum Library 10:00 12:00 What's the best way of preventing new entries from overlapping an existing schedule, like say if Miss Scarlet wants to reserve the

问题 I've seen this sort of problems a few times and am trying to decide the best way of storing ranges in a non-overlapping manner. For example, when scheduling some sort of resource that only one person can use at a time. Mostly what I've seen is something like this: PERSON ROOM START_TIME END_TIME Col. Mustard Library 08:00 10:00 Prof. Plum Library 10:00 12:00 What's the best way of preventing new entries from overlapping an existing schedule, like say if Miss Scarlet wants to reserve the

问题 I'm importing a CSV file of ~150k rows into a MySQL (InnoDB) table. At some point during the import, there's a failure because of a foreign key constraint error. It shows which column the failure is occuring on: Error Code: 1452. Cannot add or update a child row: a foreign key constraint fails (`db`.`table`, CONSTRAINT `fk` FOREIGN KEY (`otherTableId`) REFERENCES `otherTable` (`otherTableId`)) Is it possible to "catch" what that value is? I haven't tried anything yet, because I don't know

问题 I'm importing a CSV file of ~150k rows into a MySQL (InnoDB) table. At some point during the import, there's a failure because of a foreign key constraint error. It shows which column the failure is occuring on: Error Code: 1452. Cannot add or update a child row: a foreign key constraint fails (`db`.`table`, CONSTRAINT `fk` FOREIGN KEY (`otherTableId`) REFERENCES `otherTable` (`otherTableId`)) Is it possible to "catch" what that value is? I haven't tried anything yet, because I don't know

问题 I'm importing a CSV file of ~150k rows into a MySQL (InnoDB) table. At some point during the import, there's a failure because of a foreign key constraint error. It shows which column the failure is occuring on: Error Code: 1452. Cannot add or update a child row: a foreign key constraint fails (`db`.`table`, CONSTRAINT `fk` FOREIGN KEY (`otherTableId`) REFERENCES `otherTable` (`otherTableId`)) Is it possible to "catch" what that value is? I haven't tried anything yet, because I don't know

问题 Hey this is the code I use to set the constraints with auto layout for my View Elements: TimeLabel.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ TimeLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor), TimeLabel.topAnchor.constraint(equalTo: view.topAnchor, constant: -30), TimeLabel.widthAnchor.constraint(equalToConstant: 300), TimeLabel.heightAnchor.constraint(equalToConstant: 300) ]) But it doesn't work! When I change the simulator from iPhone 11 to

问题 How can I restrict the keys of an object to only those that return a certain type? In the example below I want to ensure that the type of the property is a function, so that I can execute obj[key]() . interface IObj{ p1:string, p2:number, p3:()=>void } const obj:IObj = { p1:'str', p2:5, p3:()=>void 0 } function fun<TKey extends keyof IObj>(key: IObj[TKey] extends ()=>void? TKey:never){ const p = obj[key] p(); // This expression is not callable. // Not all constituents of type 'string | number

问题 Anchor constraints simplify adding constraints but the multiplier property available in storyboard does not seem to be available for all types of constraints. For example, as per the answer here, you can center a label in a view with: view.addSubview(loadingLabel) loadingLabel.translatesAutoresizingMaskIntoConstraints = false loadingLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true loadingLabel.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true