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All questions of Stacks and Queues for Software Development Exam
Which data structure follows the Last-In-First-Out (LIFO) principle?- a)Stack
- b)Queue
- c)Linked List
- d)Heap
Correct answer is option 'A'. Can you explain this answer?
Which data structure follows the Last-In-First-Out (LIFO) principle?
a)
Stack
b)
Queue
c)
Linked List
d)
Heap
|
Hackers World answered |
Stacks follow the Last-In-First-Out (LIFO) principle, where the last element added is the first one to be removed.
What will be the output of the following code?
#include <iostream>
#include <queue>
using namespace std;int main() {
queue<int> myQueue;
myQueue.push(1);
myQueue.push(2);
myQueue.push(3);
while (!myQueue.empty()) {
cout << myQueue.front() << " ";
myQueue.pop();
}
return 0;
}- a)1 2 3
- b)3 2 1
- c)1 3 2
- d)2 1 3
Correct answer is option 'A'. Can you explain this answer?
What will be the output of the following code?
#include <iostream>
#include <queue>
using namespace std;
#include <iostream>
#include <queue>
using namespace std;
int main() {
queue<int> myQueue;
myQueue.push(1);
myQueue.push(2);
myQueue.push(3);
while (!myQueue.empty()) {
cout << myQueue.front() << " ";
myQueue.pop();
}
return 0;
}
queue<int> myQueue;
myQueue.push(1);
myQueue.push(2);
myQueue.push(3);
while (!myQueue.empty()) {
cout << myQueue.front() << " ";
myQueue.pop();
}
return 0;
}
a)
1 2 3
b)
3 2 1
c)
1 3 2
d)
2 1 3
|
Qudrat Chauhan answered |
The code pushes the elements 1, 2, and 3 onto the queue. The while loop dequeues elements from the queue and prints them until the queue becomes empty.
What will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;int main() {
stack<int> myStack;
myStack.push(10);
myStack.push(20);
myStack.push(30);
myStack.pop();
cout << myStack.size() << endl;
return 0;
}- a)0
- b)1
- c)2
- d)3
Correct answer is option 'C'. Can you explain this answer?
What will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;
#include <iostream>
#include <stack>
using namespace std;
int main() {
stack<int> myStack;
myStack.push(10);
myStack.push(20);
myStack.push(30);
myStack.pop();
cout << myStack.size() << endl;
return 0;
}
stack<int> myStack;
myStack.push(10);
myStack.push(20);
myStack.push(30);
myStack.pop();
cout << myStack.size() << endl;
return 0;
}
a)
0
b)
1
c)
2
d)
3
|
Amrutha Datta answered |
Understanding the Code
The provided C++ code utilizes the standard library's stack container to manage a collection of integers. Here's a breakdown of the operations performed:
Stack Operations
- Initialization: A stack named `myStack` is created.
- Pushing Elements:
- `myStack.push(10);` - The integer 10 is added to the stack.
- `myStack.push(20);` - The integer 20 is added to the stack.
- `myStack.push(30);` - The integer 30 is added to the stack.
After these operations, the stack contains three elements: 10, 20, and 30.
Pop Operation
- Removing the Top Element:
- `myStack.pop();` - This operation removes the top element of the stack, which is 30. After this operation, the stack now contains the elements 10 and 20.
Calculating the Size
- Getting the Size:
- `cout < mystack.size()="">< endl;`="" -="" this="" line="" prints="" the="" current="" size="" of="" the="" stack.="" since="" we="" removed="" one="" element="" (30),="" the="" stack="" now="" has="" two="" remaining="" elements="" (10="" and="">
Conclusion
- The final output of `myStack.size()` is 2, as there are two elements left in the stack after the pop operation.
Thus, the correct answer is option 'C', which corresponds to the size of the stack being 2.
The provided C++ code utilizes the standard library's stack container to manage a collection of integers. Here's a breakdown of the operations performed:
Stack Operations
- Initialization: A stack named `myStack` is created.
- Pushing Elements:
- `myStack.push(10);` - The integer 10 is added to the stack.
- `myStack.push(20);` - The integer 20 is added to the stack.
- `myStack.push(30);` - The integer 30 is added to the stack.
After these operations, the stack contains three elements: 10, 20, and 30.
Pop Operation
- Removing the Top Element:
- `myStack.pop();` - This operation removes the top element of the stack, which is 30. After this operation, the stack now contains the elements 10 and 20.
Calculating the Size
- Getting the Size:
- `cout < mystack.size()="">< endl;`="" -="" this="" line="" prints="" the="" current="" size="" of="" the="" stack.="" since="" we="" removed="" one="" element="" (30),="" the="" stack="" now="" has="" two="" remaining="" elements="" (10="" and="">
Conclusion
- The final output of `myStack.size()` is 2, as there are two elements left in the stack after the pop operation.
Thus, the correct answer is option 'C', which corresponds to the size of the stack being 2.
Which of the following operations is NOT supported by a stack?- a)Push
- b)Pop
- c)Peek
- d)Enqueue
Correct answer is option 'D'. Can you explain this answer?
Which of the following operations is NOT supported by a stack?
a)
Push
b)
Pop
c)
Peek
d)
Enqueue
|
Code Nation answered |
Enqueue is an operation supported by a queue, not a stack. Enqueue adds an element to the rear end of a queue.
Given a stack st with elements [1, 2, 3, 4, 5], what will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;void display(stack<int>& st) {
while (!st.empty()) {
cout << st.top() << " ";
st.pop();
}
}int main() {
stack<int> st;
st.push(1);
st.push(2);
st.push(3);
display(st);
return 0;
}- a)1 2 3
- b)3 2 1
- c)Compile-time error
- d)Run-time error
Correct answer is option 'B'. Can you explain this answer?
Given a stack st with elements [1, 2, 3, 4, 5], what will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;
#include <iostream>
#include <stack>
using namespace std;
void display(stack<int>& st) {
while (!st.empty()) {
cout << st.top() << " ";
st.pop();
}
}
while (!st.empty()) {
cout << st.top() << " ";
st.pop();
}
}
int main() {
stack<int> st;
st.push(1);
st.push(2);
st.push(3);
display(st);
return 0;
}
stack<int> st;
st.push(1);
st.push(2);
st.push(3);
display(st);
return 0;
}
a)
1 2 3
b)
3 2 1
c)
Compile-time error
d)
Run-time error
|
Anushka Choudhary answered |
Understanding the Code
The provided C++ code manipulates a stack and displays its contents. Let's break down the key components.
Stack Initialization
- A stack of integers is created.
- Elements 1, 2, and 3 are pushed onto the stack in that order.
Function Definition
- The `display` function takes a stack by reference.
- It uses a `while` loop to print the top element and then pops it from the stack until the stack is empty.
Function Execution
- When calling `display(st)` in `main()`, the stack contains only the elements 1, 2, and 3.
- The `display` function will print the top element (3), then pop it.
- This process continues, printing 2 next, then popping it, and finally printing 1.
Result of the Code
- The output sequence will be 3, 2, 1 since the stack is a Last In, First Out (LIFO) structure.
Final Output
- Therefore, the correct answer is option 'B': 3 2 1.
In summary, the stack's behavior leads to the last elements pushed being the first ones to be displayed, resulting in the output being reversed from their original insertion order.
The provided C++ code manipulates a stack and displays its contents. Let's break down the key components.
Stack Initialization
- A stack of integers is created.
- Elements 1, 2, and 3 are pushed onto the stack in that order.
Function Definition
- The `display` function takes a stack by reference.
- It uses a `while` loop to print the top element and then pops it from the stack until the stack is empty.
Function Execution
- When calling `display(st)` in `main()`, the stack contains only the elements 1, 2, and 3.
- The `display` function will print the top element (3), then pop it.
- This process continues, printing 2 next, then popping it, and finally printing 1.
Result of the Code
- The output sequence will be 3, 2, 1 since the stack is a Last In, First Out (LIFO) structure.
Final Output
- Therefore, the correct answer is option 'B': 3 2 1.
In summary, the stack's behavior leads to the last elements pushed being the first ones to be displayed, resulting in the output being reversed from their original insertion order.
What will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;int main() {
stack<int> myStack;
myStack.push(10);
myStack.push(20);
myStack.push(30);
cout << myStack.top() << endl;
myStack.pop();
cout << myStack.top() << endl;
return 0;
}- a)10, 20
- b)30, 20
- c)20, 30
- d)10, 30
Correct answer is option 'C'. Can you explain this answer?
What will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;
#include <iostream>
#include <stack>
using namespace std;
int main() {
stack<int> myStack;
myStack.push(10);
myStack.push(20);
myStack.push(30);
cout << myStack.top() << endl;
myStack.pop();
cout << myStack.top() << endl;
return 0;
}
stack<int> myStack;
myStack.push(10);
myStack.push(20);
myStack.push(30);
cout << myStack.top() << endl;
myStack.pop();
cout << myStack.top() << endl;
return 0;
}
a)
10, 20
b)
30, 20
c)
20, 30
d)
10, 30
|
Tanuja Mishra answered |
The code pushes the elements 10, 20, and 30 onto the stack. The top() function returns the value at the top of the stack, which is 30. After popping an element, the new top is 20.
What will be the output of the following code?
#include <iostream>
#include <queue>
using namespace std;int main() {
queue<int> myQueue;
myQueue.push(5);
myQueue.push(10);
myQueue.push(15);
cout << myQueue.front() << endl;
myQueue.pop();
cout << myQueue.front() << endl;
return 0;
}- a)5, 10
- b)15, 10
- c)10, 15
- d)5, 15
Correct answer is option 'A'. Can you explain this answer?
What will be the output of the following code?
#include <iostream>
#include <queue>
using namespace std;
#include <iostream>
#include <queue>
using namespace std;
int main() {
queue<int> myQueue;
myQueue.push(5);
myQueue.push(10);
myQueue.push(15);
cout << myQueue.front() << endl;
myQueue.pop();
cout << myQueue.front() << endl;
return 0;
}
queue<int> myQueue;
myQueue.push(5);
myQueue.push(10);
myQueue.push(15);
cout << myQueue.front() << endl;
myQueue.pop();
cout << myQueue.front() << endl;
return 0;
}
a)
5, 10
b)
15, 10
c)
10, 15
d)
5, 15
|
Maulik Sen answered |
Explanation:
Queue Operations:
- Initially, the queue is empty.
- We push three elements (5, 10, 15) into the queue.
- The front of the queue is the first element, which is 5.
- We pop the front element from the queue.
- The front of the queue now becomes 10.
Output:
- After the first push operation, the queue contains {5}.
- After the second push operation, the queue contains {5, 10}.
- After the third push operation, the queue contains {5, 10, 15}.
- The front of the queue is 5.
- After the pop operation, the queue contains {10, 15}.
- The front of the queue is now 10.
Therefore, the output of the code will be:
5
10
Queue Operations:
- Initially, the queue is empty.
- We push three elements (5, 10, 15) into the queue.
- The front of the queue is the first element, which is 5.
- We pop the front element from the queue.
- The front of the queue now becomes 10.
Output:
- After the first push operation, the queue contains {5}.
- After the second push operation, the queue contains {5, 10}.
- After the third push operation, the queue contains {5, 10, 15}.
- The front of the queue is 5.
- After the pop operation, the queue contains {10, 15}.
- The front of the queue is now 10.
Therefore, the output of the code will be:
5
10
Given a queue q with elements [1, 2, 3, 4, 5], what will be the output of the following code?
#include <iostream>
#include <queue>
using namespace std;void display(queue<int>& q) {
while (!q.empty()) {
cout << q.front() << " ";
q.pop();
}
}int main() {
queue<int> q;
q.push(1);
q.push(2);
q.push(3);
display(q);
return 0;
}- a)1 2 3
- b)3 2 1
- c)Compile-time error
- d)Run-time error
Correct answer is option 'A'. Can you explain this answer?
Given a queue q with elements [1, 2, 3, 4, 5], what will be the output of the following code?
#include <iostream>
#include <queue>
using namespace std;
#include <iostream>
#include <queue>
using namespace std;
void display(queue<int>& q) {
while (!q.empty()) {
cout << q.front() << " ";
q.pop();
}
}
while (!q.empty()) {
cout << q.front() << " ";
q.pop();
}
}
int main() {
queue<int> q;
q.push(1);
q.push(2);
q.push(3);
display(q);
return 0;
}
queue<int> q;
q.push(1);
q.push(2);
q.push(3);
display(q);
return 0;
}
a)
1 2 3
b)
3 2 1
c)
Compile-time error
d)
Run-time error
|
|
Qudrat Chauhan answered |
The display() function dequeues elements from the queue and prints them until the queue becomes empty. The elements are printed in the order of their insertion, resulting in "1 2 3".
Which data structure follows the First-In-First-Out (FIFO) principle?- a)Stack
- b)Queue
- c)Linked List
- d)Heap
Correct answer is option 'B'. Can you explain this answer?
Which data structure follows the First-In-First-Out (FIFO) principle?
a)
Stack
b)
Queue
c)
Linked List
d)
Heap
|
Tom Tattle answered |
Queues follow the First-In-First-Out (FIFO) principle, where the first element added is the first one to be removed.
What is the time complexity for pushing an element onto a stack?- a)O(1)
- b)O(log n)
- c)O(n)
- d)O(n2)
Correct answer is option 'A'. Can you explain this answer?
What is the time complexity for pushing an element onto a stack?
a)
O(1)
b)
O(log n)
c)
O(n)
d)
O(n2)
|
|
Tom Tattle answered |
Pushing an element onto a stack takes constant time, regardless of the stack's size.
Given an input string s = "abcde", which of the following code snippets correctly stores the characters of the string into a stack st?
(I)
stack<char> st;
for (int i = 0; i < s.length(); i++) {
st.push(s[i]);
}
(II)
stack<char> st;
for (int i = s.length() - 1; i >= 0; i--) {
st.push(s[i]);
}(III)
stack<char> st;
for (int i = 0; i < s.length(); i++) {
st.push_back(s[i]);
}- a)I only
- b)II only
- c)I and II only
- d)II and III only
Correct answer is option 'B'. Can you explain this answer?
Given an input string s = "abcde", which of the following code snippets correctly stores the characters of the string into a stack st?
(I)
stack<char> st;
for (int i = 0; i < s.length(); i++) {
st.push(s[i]);
}
(II)
stack<char> st;
for (int i = s.length() - 1; i >= 0; i--) {
st.push(s[i]);
}
(I)
stack<char> st;
for (int i = 0; i < s.length(); i++) {
st.push(s[i]);
}
(II)
stack<char> st;
for (int i = s.length() - 1; i >= 0; i--) {
st.push(s[i]);
}
(III)
stack<char> st;
for (int i = 0; i < s.length(); i++) {
st.push_back(s[i]);
}
stack<char> st;
for (int i = 0; i < s.length(); i++) {
st.push_back(s[i]);
}
a)
I only
b)
II only
c)
I and II only
d)
II and III only
|
|
Qudrat Chauhan answered |
The code snippet II correctly stores the characters of the input string into a stack by iterating over the string in reverse order.
What will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;int main() {
stack<int> myStack;
myStack.push(1);
myStack.push(2);
myStack.push(3);
while (!myStack.empty()) {
cout << myStack.top() << " ";
myStack.pop();
}
return 0;
}- a)1 2 3
- b)3 2 1
- c)3 1 2
- d)2 3 1
Correct answer is option 'B'. Can you explain this answer?
What will be the output of the following code?
#include <iostream>
#include <stack>
using namespace std;
#include <iostream>
#include <stack>
using namespace std;
int main() {
stack<int> myStack;
myStack.push(1);
myStack.push(2);
myStack.push(3);
while (!myStack.empty()) {
cout << myStack.top() << " ";
myStack.pop();
}
return 0;
}
stack<int> myStack;
myStack.push(1);
myStack.push(2);
myStack.push(3);
while (!myStack.empty()) {
cout << myStack.top() << " ";
myStack.pop();
}
return 0;
}
a)
1 2 3
b)
3 2 1
c)
3 1 2
d)
2 3 1
|
|
Qudrat Chauhan answered |
The code pushes the elements 1, 2, and 3 onto the stack. The while loop pops elements from the stack and prints them until the stack becomes empty.
Which of the following is an example of a stack implementation?- a)Depth-First Search (DFS)
- b)Breadth-First Search (BFS)
- c)Dijkstra's Algorithm
- d)Prim's Algorithm
Correct answer is option 'A'. Can you explain this answer?
Which of the following is an example of a stack implementation?
a)
Depth-First Search (DFS)
b)
Breadth-First Search (BFS)
c)
Dijkstra's Algorithm
d)
Prim's Algorithm
|
|
Code Nation answered |
Depth-First Search (DFS) is an example of a graph traversal algorithm that uses a stack to keep track of vertices.
Given an input string s = "abcde", which of the following code snippets correctly stores the characters of the string into a queue q?
(I)
queue<char> q;
for (int i = 0; i < s.length(); i++) {
q.push(s[i]);
}
(II)
queue<char> q;
for (int i = s.length() - 1; i >= 0; i--) {
q.push(s[i]);
}
(III)
queue<char> q;
for (int i = 0; i < s.length(); i++) {
q.push_back(s[i]);
}- a)I only
- b)II only
- c)I and II only
- d)II and III only
Correct answer is option 'A'. Can you explain this answer?
Given an input string s = "abcde", which of the following code snippets correctly stores the characters of the string into a queue q?
(I)
queue<char> q;
for (int i = 0; i < s.length(); i++) {
q.push(s[i]);
}
(II)
queue<char> q;
for (int i = s.length() - 1; i >= 0; i--) {
q.push(s[i]);
}
(III)
queue<char> q;
for (int i = 0; i < s.length(); i++) {
q.push_back(s[i]);
}
(I)
queue<char> q;
for (int i = 0; i < s.length(); i++) {
q.push(s[i]);
}
(II)
queue<char> q;
for (int i = s.length() - 1; i >= 0; i--) {
q.push(s[i]);
}
(III)
queue<char> q;
for (int i = 0; i < s.length(); i++) {
q.push_back(s[i]);
}
a)
I only
b)
II only
c)
I and II only
d)
II and III only
|
|
Qudrat Chauhan answered |
The code snippet I correctly stores the characters of the input string into a queue by iterating over the string in the normal order.
Given a stack st with elements [1, 2, 3, 4, 5], what will be the value of x after the following code execution?
#include <iostream>
#include <stack>
using namespace std;int main() {
stack<int> st;
st.push(1);
st.push(2);
st.push(3);
int x = st.top();
st.pop();
x += st.top();
return 0;
}- a)1
- b)2
- c)3
- d)4
Correct answer is option 'D'. Can you explain this answer?
Given a stack st with elements [1, 2, 3, 4, 5], what will be the value of x after the following code execution?
#include <iostream>
#include <stack>
using namespace std;
#include <iostream>
#include <stack>
using namespace std;
int main() {
stack<int> st;
st.push(1);
st.push(2);
st.push(3);
int x = st.top();
st.pop();
x += st.top();
return 0;
}
stack<int> st;
st.push(1);
st.push(2);
st.push(3);
int x = st.top();
st.pop();
x += st.top();
return 0;
}
a)
1
b)
2
c)
3
d)
4
|
|
Qudrat Chauhan answered |
The code stores the value at the top of the stack (3) in variable x. Then, it pops an element from the stack and adds its value (2) to x. Therefore, x becomes 3 + 2 = 5.
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DSA in C++
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