stack

问题 This question already has answers here : Reshaping data.frame from wide to long format (9 answers) Closed 2 years ago . I have a data frame that I would like to stack in R so that I end up with three columns. Below cis some example data in its current format. > dput(df) structure(list(Day = c("d1", "d2", "d3", "d4", "d5", "d6", "d7", "d8", "d9", "d10"), A1 = c(14L, 24L, 22L, NA, NA, NA, NA, NA, NA, NA), A2 = c(9L, 15L, 34L, 2L, 12L, 34L, 234L, 34L, NA, NA ), A3 = c(3L, 4L, 19L, 76L, 34L, 34L,

问题 This question already has answers here : Reshaping data.frame from wide to long format (9 answers) Closed 2 years ago . I have a data frame that I would like to stack in R so that I end up with three columns. Below cis some example data in its current format. > dput(df) structure(list(Day = c("d1", "d2", "d3", "d4", "d5", "d6", "d7", "d8", "d9", "d10"), A1 = c(14L, 24L, 22L, NA, NA, NA, NA, NA, NA, NA), A2 = c(9L, 15L, 34L, 2L, 12L, 34L, 234L, 34L, NA, NA ), A3 = c(3L, 4L, 19L, 76L, 34L, 34L,

问题 I got one simple question: which kind of data structure is a stack? Is it a static or dynamic data structure? I was looking for the answer and couldn't find it, therefore I got my own "explanation" - I guess, when you can implement it either by using an array or a linked list, it can be... both?, depending on implementation? Does my reasoning make any sense? 回答1: By definition, a static data structure has fixed size. If you can limit the size of your stack to some pre-determined number, your

问题 Most of the time we can assume that stack is faster and cleaner. No memory fragmentation, easier to cache, quick allocation. That's also why people always assume that static buffer allocated on stack is much faster than dynamic buffer on heap. Is it? One misconception I see most of the time is that people assume that c99 extension (which is supported as non-standard extension in common C++ compilers like GCC) allocating dynamic sized array on stack will perform as fast as static size. I think

问题 void push(stack *head, int valuee) { if(head->next==NULL && head->value==-1) { head->value = valuee; printf("First element %d inserted\n",valuee); } else { stack *temp = new stack; temp->value = valuee; temp->next = head; head = temp; printf("Element %d inserted\n",valuee); } } First element is inserted properly but when i continue inserting elements, none of the elements are inserted after the first one. Read somewhere that i have to pass pointer to pointer of stack but I did this same thing

问题 I knew what is stack and heap, but when I did some experiments on this topic, I found something surprising. int i,j; std::cout<< &i << "\n"; std::cout<< &j << "\n"; Results: 0x7a893a29e5b8 0x7a893a29e5bc That means stack is toward to high address, and not to low address which is shown by below graph. 来源： https://stackoverflow.com/questions/61540247/stack-and-heap-about-memory-address-question

问题 I tested the following codes: void f1() { int x = 1; cout << "f1 : " << &x << endl; } void f2() { int x = 2; cout << "f2 : " << &x << endl; } void f3() { { int x = 3; cout << "f3_1: " << &x << endl; } { int x = 4; cout << "f3_2: " << &x << endl; } } int main() { f1(); f2(); f3(); } in release build, the output is... f1 : 00FAF780 f2 : 00FAF780 f3_1: 00FAF780 f3_2: 00FAF780 <-- I expected but in debug build, f1 : 012FF908 f2 : 012FF908 f3_1: 012FF908 f3_2: 012FF8FC <-- what?? I thought the

问题 I'm creating a stack using a linked list in C. The code is as follows: struct node{ int xposition; int yposition; struct node* next; }; void pushToTop(struct node** hd, int x, int y){ struct node* curr= *hd; struct node* prev=NULL; while(curr!=NULL){ prev=curr; curr= curr->next; } struct node* ptr= (struct node*)malloc(sizeof(struct node)); ptr->xposition=x; ptr->yposition=y; ptr->next=curr; if(prev==NULL){ *hd= ptr;} else{ prev->next=ptr; } } void popFromTop(struct node** hd ){ struct node*

问题 I want to add red blinking dot on the container when it is tapped, but the dot position is not accurate. How to fix? MyApp import 'package:flutter/material.dart'; import 'blinking_dot.dart'; void main() => runApp(MyApp()); class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'Flutter Demo', theme: ThemeData( primarySwatch: Colors.blue, ), home: MyHomePage(title: 'Flutter Demo Home Page'), ); } } class MyHomePage extends StatefulWidget

问题 Find an algorithm to recursively remove all adjacent duplicates in a given string this is the original question.I have thought of an algorithm using stacks. 1.Initialize a stack and a char_popped variable 2.Push the first char of str into the stack. 3.now iterate through the characters of string. if the top of stack matches with the character { pop the character from the stack, char_popped=character } else { if(character==char_popped) {DONT DO ANYTHING} else push the character on the stack